Seizures of drugs in England and Wales: user guide

1. Introduction

This user guide is intended as a useful reference with explanatory notes on the issues and classifications key to the production and presentation of the Home Office’s annual release Seizures of drugs in England and Wales statistics. Staff in the Drugs Supply and Harms Research Team, which is part of the Drugs Exploitation and Abuse Analysis Unit, prepare the annual release and accompanying datasets.

1.1 Statistics covered

The statistics in Seizures of drugs in England and Wales relate to the seizures of drugs controlled under The Misuse of Drugs Act (MDA) 1971, which came into force on 1 July 1973, and The Psychoactive Substances Act (PSA) 2016, which came into force on 26 May 2016. They cover seizures made during the year by police forces in England and Wales (including the British Transport Police) and Border Force. Border Force used to be part of the UK Border Agency (UKBA). Although Border Force will have made seizures outside the land territory of England and Wales (e.g. Scotland, Northern Ireland), such seizures are excluded from figures presented in the publication.

The release draws together statistics on the following topics:

• number of seizures
• quantity of drugs seized
• seizures by authority (i.e. comparisons between police forces and Border Force)

Seizures of drugs statistics are presented on a financial year (FY) basis (1 April to 31 March).

Seizures involving more than one drug were counted as a single seizure in the total number of seizures. However, they were counted separately against each individual drug or drug class involved (see Chapter 3). Annual movements in quantities were often heavily affected by a few very large seizures.

Further details on coverage in this release and classification of drugs under the MDA are in Chapter 3.

The Home Office first collated drug seizure statistics in an electronic format in 1974, originally covering the United Kingdom rather than England and Wales. Since the MDA was introduced, there have been various changes to which drugs are covered by the Act and to recording practices by police forces and other agencies. As such, drug seizure statistics are not directly comparable from year to year. Nor are they a measure of drug prevalence in society.

In the financial year ending 31 March 2018, information on seizures of new psychoactive substances (NPS) was recorded systematically across police forces and Border Force for the first time. NPS refers to newly available drugs that mimic the effect of existing drugs such as cannabis, ecstasy, and powder cocaine. Some NPS are controlled under the MDA, while other NPS are illegal to supply, produce and import under the Psychoactive Substances Act 2016. Data on NPS seizures were included in publications for years ending March 2018 to 2021, and designated as Experimental Statistics, as they are not fully developed and do not meet the rigorous quality standards of Official Statistics.

1.2 Quality and methodology

The data covered by this release are by-products of police administrative processes and form part of the statutory Annual Data Requirement between the Home Office and police forces (including Border Force).

The published figures on drug seizures are sourced from police forces’ operational records. Although care is taken in completing and analysing the returns used to compile the figures in this release, the figures are subject to the inaccuracies of any large-scale recording system of this kind that involves different organisations. The Home Office is continually working with police forces to understand fully the processes and limitations of the data.

So, to ensure the reliability of police forces’ data, a reconciliation exercise (described in Appendix A) is conducted whereby each police force is asked to check its own data and supply revised figures where necessary. Any identified deficiencies for a particular year’s data are listed in the ‘Data quality and interpreting the figures’ section of that year’s main release.

The section below considers the process before the data are submitted to the Home Office. It outlines the key characteristics and limitations of the statistics. Where there are limitations, the implications of these in terms of uses of the data are outlined. The strengths and limitations of the data vary from force to force depending on specific internal data collection and quality assurance procedures.

At the start of the data collection process, the Home Office sends an Excel template to every police force to compile their drug seizure statistics. This template has comprehensive checks built into it to ensure any erroneous values are picked up at this data collection stage. The template also ensures that each drug is correctly classified, and that the preparation type (e.g. kilograms, doses etc.) entered by the force is valid for the specified drug. Though this process highlights any initial quality concerns, there are other limitations to the data (List 1).

List 1: Limitations and implications of drug seizures data

Limitations: Data relies on police forces correctly recording and entering drug seizures on their systems.
Implications: Although any obvious errors would be highlighted in the quality assurance checks conducted by both the data suppliers and the data producers, it is possible that some data may not be totally accurate. This is likely to be the case with any large-scale recording system that involves several different organisations. More details are provided below on how Home Office analysts work with police forces to ensure data quality.

Limitations: Not all drugs seized by police forces are tested by forensics. For drugs that are not tested by forensics, accuracy of the data relies on the officer correctly identifying the substance, or the offender stating what the substance is.
Implications: There is a small chance that some drugs have not been identified (and therefore classified) correctly. This will not affect the total number of drugs seized but could impact the more detailed statistics. It is unlikely that the main drugs reported on in the publication would be misclassified (i.e. cannabis, cocaine, ecstasy etc.)

Limitations: Forces can seize drugs in different preparation types. The Home Office uses conversion factors (last updated in 2005) to convert the quantity of seizures into one comparable unit.
Implications: Since the conversion factors have not been updated for some time, it is possible that some quantity data (especially for those drugs where quantity is reported in terms of doses) is not entirely accurate. However, the same conversion factors have been used throughout the time series so the data on trends can be considered reliable.

Limitations: Changes in force systems meaning only a partial return can be submitted to the Home Office.
Implications: Several forces have changed their data recording systems in the past few years and sometimes this has led to the loss of some drug seizures data. From the year ending March 2015 publication onwards, it was decided that rather than just reporting the partial data return, the Home Office would impute the missing data using the data supplied.

Users should be aware that this method has been used. They can identify which forces used this method, in the footnotes for the tables. More information on how data have been imputed is given below.

Limitations: During the quality checks for the year ending March 2015 publication, it became apparent that police forces had different ways of recording seizures of large amounts of cannabis plants from one cannabis farm.

To ensure consistency in recording practices, forces received guidance explaining that if it is not possible to count every cannabis plant seized, then an estimate should be made instead.

Implications: The number of cannabis plants seized by police forces may be estimates in some cases. This does not affect the total number of seizures but will impact the quantity of plants seized.

1.2.1 Quality assurance by the Home Office

All the data received by the Home Office undergo a strict quality assurance process to ensure the data are fit for purpose and published to the highest standard. Any data quality issues are flagged and subsequently resolved with forces. Before publication, data are aggregated into tables and sent back to forces to be signed off prior to publication to ensure they are accurate. Details of any known data quality issues are included in the relevant part of the bulletin, and/or data tables.

While all data undergo a thorough quality assurance process, the level varies according to factors such as the type of drug seized, the likelihood of error in the data, and what the data are used for. Data that are widely used and that inform important and high-profile decisions will undergo the highest level of quality assurance. Other data will undergo a more limited but proportionate level. The quality assurance checks include looking for:

• missing and/or incomplete data
• inconsistencies in the data
• extreme values
• invalid quantities
• known issues as mentioned in List 1

Once these checks have been completed, Home Office analysts undertake trend analysis to look for unusual or unexpected trends in the data. Any inconsistencies or unusual trends are flagged to forces. They are then asked to explain the trends or submit amended data.

Where an error is spotted, Home Office analysts consider whether this is likely to be a force-specific issue, or whether other forces should be notified to ensure consistency of data between forces. Recent examples of errors and or issues spotted, and the action subsequently taken, include:

Incorrect quantity of drugs recorded for LSD

In 2020, Home Office analysts identified four occasions where seizures of LSD had been recorded against the ‘weighed’ preparation type. After applying conversion factors these seizures would have been converted to tens of thousands of doses. After querying these seizures with the forces involved, three entries were found to be erroneous and were excluded from the publication.

Recording of number of cannabis plants per seizure

In the year ending March 2015, analysis of the data by force showed that the number of plants seized per seizure showed a wide variation, with a few forces reporting particularly low numbers per seizure. This was discussed with these forces, who reported that where many plants were seized (too many to count) the forces were entering ‘1’ as a default. The guidance was updated to ask forces to count the number of plants or at least enter a reasonable estimate, rather than using a default value of 1.

For year ending March 2021, several forces were found to have recorded 1 plant as a ‘default’, but when this was discussed with them, they checked and found that some such entries were incorrect. They then revised and resubmitted their data accordingly. Three forces also did this for the 2019/20 reporting year and their data have also been updated.

However, some forces reported that they have had more seizures of single cannabis plants in year ending March 2021 than usual – as some users were found to have been growing the plants individually at home, (for personal consumption), during the COVID-19 ‘lockdown’ phases.

1.3 Imputation of data

In some years, certain forces could not supply the Home Office with accurate drug seizures data. This may be due to several reasons, including:

• the police force has changed processes around the recording of drug seizures which have taken time to bed in
• changes in police force IT systems
• identification of errors by either the police force or Home Office analysts

Where a police force could not send data deemed suitable for publication, the Home Office has imputed values for that force. This is done with the agreement of the police force in question, and only when the Home Office and force agree that imputation of data is likely to give a more accurate figure for their police force than using the data they hold. The imputation methods used in financial year ending (YE) 31 March 2021 and in previous years are in List 2.

List 2: Imputation methods used for missing or incomplete data from police forces

Police force: Hampshire Constabulary
YE March: 2013
Data supplied: None.
Imputation method used: Values estimated using midpoints of their figures for years ending March 2012 and 2014.

Police force: Surrey Police
YE March: 2013
Data supplied: Low figures.
Imputation method used: Values estimated using midpoints of their figures for years ending March 2012 and 2014.

Police force: Gwent Police
YE March: 2014
Data supplied: For 10 months only.
Imputation method used: Full year values estimated using extrapolation methods.

Police force: Bedfordshire Police
YE March: 2015
Data supplied: None.
Imputation method used: Values estimated by multiplying YE 2014 figures by relevant total England and Wales change for years ending March 2014 and 2015 for all non-estimated values.

Police force: Hampshire Constabulary
YE March: 2015
Data supplied: None.
Imputation method used: Values estimated by multiplying YE 2014 figures by relevant total England and Wales change for years ending March 2014 and 2015 for all non-estimated values.

Police force: Bedfordshire Police
YE March: 2016
Data supplied: None.
Imputation method used: Values estimated using the change in forces’ Police Recorded Crime (PRC) data on drug-related offences for years ending March 2015 and 2016.

Police force: Dorset Police
YE March: 2016
Data supplied: Only 81%.
Imputation method used: Full year values estimated using extrapolation methods.

Police force: Essex Police
YE March: 2016
Data supplied: None.
Imputation method used: Values estimated using the change in forces’ PRC data on drug-related offences for years ending March 2015 and 2016.

Police force: Leicestershire Police
YE March: 2016
Data supplied: None.
Imputation method used: Values estimated using the change in forces’ PRC data on drug-related offences for years ending March 2015 and 2016.

Police force: Kent Police
YE March: 2017
Data supplied: None.
Imputation method used: Values estimated by multiplying the force’s YE 2016 values by the total England and Wales change in the corresponding values for years ending March 2017 and 2018, excluding estimated values.

Police force: Kent Police
YE March: 2018
Data supplied: None.
Imputation method used: Values estimated by multiplying force’s YE 2017 values by the total England and Wales change in the corresponding values for years ending March 2017 and 2018, excluding estimated values.

Police force: Hertfordshire Constabulary
YE March: 2019
Data supplied: None.
Imputation method used: Values estimated by multiplying force’s YE 2018 values by the total England and Wales change in the corresponding values for years ending March 2018 and 2019, excluding estimated values.

Police force: Kent Police
YE March: 2019
Data supplied: None.
Imputation method used: Values estimated by multiplying force’s YE 2018 values by the total England and Wales change in the corresponding values for years ending March 2018 and 2019, excluding estimated values.

Police force: Lincolnshire Constabulary
YE March: 2019
Data supplied: Partial.
Imputation method used: Values estimated by multiplying force’s YE 2018 values by the total England and Wales change in the corresponding values for years ending March 2018 and 2019, excluding estimated values.

Police force: Hertfordshire Constabulary
YE March: 2020
Data supplied: None.
Imputation method used: Values estimated by multiplying force’s YE 2019 values by the total England and Wales change in the corresponding values for years ending March 2019 and 2020, excluding estimated values.

Police force: Kent Police
YE March: 2020
Data supplied: None.
Imputation method used: Values estimated by multiplying force’s YE 2019 values by the total England and Wales change in the corresponding values for years ending March 2019 and 2020, excluding estimated values.

Police force: Lincolnshire Constabulary
YE March: 2020
Data supplied: None.
Imputation method used: Values estimated by multiplying force’s YE 2019 values by the total England and Wales change in the corresponding values for years ending March 2019 and 2020, excluding estimated values.

Police force: Greater Manchester Police
YE March: 2020
Data supplied: None.
Imputation method used: Values estimated by multiplying force’s YE 2019 values by the total England and Wales change in the corresponding values for years ending March 2019 and 2020, excluding estimated values.

Police force: Hertfordshire Constabulary
YE March: 2021
Data supplied: None
Imputation method used: Values estimated by multiplying force’s YE 2020 values by the total England and Wales change in the corresponding values for years ending March 2020 and 2021, excluding estimated values.

Police force: Kent Police
YE March: 2021
Data supplied: None
Imputation method used: Values estimated by multiplying force’s YE 2020 values by the total England and Wales change in the corresponding values for years ending March 2020 and 2021, excluding estimated values.

Police force: Staffordshire Police
YE March: 2021
Data supplied: Partial
Imputation method used: Values estimated by multiplying force’s YE 2020 values by the total England and Wales change in the corresponding values for years ending March 2020 and 2021, excluding estimated values.

1.4 Uses

Statistics on seizures of drugs are used for a variety of purposes, which are listed below using the standard categorisation for Official Statistics (UK Statistics Authority monitoring brief 6/2010, The Uses Made of Official Statistics).

Informing the general public’s choices:

• about the state of the economy, society, and the environment: figures on drug seizures are used occasionally by the media in articles on the drug situation
• about the performance of government and public bodies: figures on numbers and quantities of seizures are requested via Parliamentary Questions and Freedom of Information cases to gauge performance in general or specific areas
• government policymaking and monitoring: the primary use of the drug seizure statistics is by international agencies, e.g. the European Monitoring Centre for Drugs and Drug Addiction (EMCDDA), to compare performance nationally
• informing public marketing campaigns: drug seizure statistics are used in anti-drug campaigns by individual police forces or nationally
• supporting third sector activity – lobbying: drug seizure statistics are used by public safety lobbies to monitor current government legislation and government policy
• facilitating academic research: researchers into policing and criminology often use police statistics such as those on workforce and recorded crime. There is limited use of drug seizure statistics in academic research because drug seizures are not considered a measure of drug prevalence

1.5 User experiences

The Home Office conducted a survey for the Seizures of drugs in England and Wales statistical release for the year ending March 2014 so that the department could assess how well it met users’ needs and might make improvements where possible.

There were 11 responses to the survey. Key points included the following.

• most respondents were students, followed by those who worked in the voluntary sector. Responses were also received from police forces, other government departments and other public organisations
• respondents who stated that they had not found the information they were looking for, sought data on specific drugs which are not currently included as individual drugs in the publication
• almost all respondents reported that they had used the data tables, over half reported they had used the main commentary, and half reported they had used the statistical news release. A third of respondents stated they had used the user guide. For those respondents that had used the tables, commentary and statistical news release, the majority reported that they were satisfied with them

1.5.1 Ongoing user engagement

In addition to carrying out surveys of users, the Home Office engages with users and stakeholders of the statistics on an ongoing basis to ensure the statistics remain as relevant as possible. These include police forces, Border Force, Public Health England, the Scottish Government, the National Crime Agency and EMCDDA. Working with these institutions allows us to share knowledge and ensure that our statistics continue to meet customers’ needs.

1.6 International comparisons

EU member states, Turkey and Norway submit data on drug seizures to EMCDDA for inclusion in its annual report. The Home Office also has a statutory requirement to provide drug seizures data to the United Nations Office on Drugs and Crime (UNODC) annually, for publication in its annual world drug report. When considering data for different countries, it is worth noting that they may relate to different time periods. They may also have been collected or recorded differently. As such, they may not be directly comparable with figures for England and Wales.

Data relating to seizures of drugs by police forces in Scotland are published by the Scottish Government. Similarly, the Police Service of Northern Ireland publishes statistics of its seizures. Both collections follow the same counting rules as those presented in the England and Wales release and, as well as providing comparisons with England and Wales, allow for a more complete UK-wide picture.

1.7 Where are the latest published figures?

Forthcoming publications are pre-announced on GOV.UK. The annual Seizures of drugs in England and Wales publication, and other Home Office statistical releases, are available from the Home Office pages of the GOV.UK website.

1.8 Feedback and enquiries

We welcome feedback on Seizures of drugs in England and Wales. If you have any comments, suggestions or enquiries, please email them to drugseizures.datacollection@homeoffice.gov.uk.

Drugs Exploitation and Abuse Analysis Unit, 2^nd floor Peel Building, 2 Marsham Street, London, SW1P 4DF.

National Statistics status

These statistics have been designated as National Statistics, following an assessment by the UK Statistics Authority’s regulatory arm. The Authority considers whether the statistics meet the highest standards of Code compliance. These include the value the statistics add to public decisions and debate, and the highest standards of trustworthiness, quality and public value.

This statistical bulletin is produced to the highest professional standards and is free from political interference. It has been produced by statisticians working in the Drugs Exploitation and Abuse Analysis Unit, in accordance with the Home Office’s statement of compliance with the Code of Practice for Official Statistics, which covers Home Office policy on revisions and other matters. The Chief Statistician, as Head of Profession, reports to the National Statistician with respect to all professional statistical matters. They oversee all Home Office National Statistics products with respect to the Code, being responsible for their timing, content and methodology.

2. Conventions used in seizures of drugs statistics

2.1 Rounding

Data are mainly provided unrounded in the data tables of Seizures of drugs in England and Wales. This is to promote transparency and allow users to exploit the data further.

However, caution should be taken when comparing small differences between time periods. The figures in the tables in this bulletin are generally shown to the last digit, in order to provide a comprehensive record of the information collected.

Percentages are rounded to the nearest percent using the round-half-away-from-zero method, meaning that in the borderline case where the fraction of the percentage is exactly 0.5, the rounded figure is equal to y + 0.5 if y is positive, and y – 0.5 if y is negative. For example, 23.5% is rounded to 24%, and -23.5% is rounded to -24%. When rounding whole numbers, the result is similar, e.g. when rounding to the nearest 100, 1,250 would be reported as 1,300.

2.2 Use of symbols

The following symbols have been used in the tables:

‘0’ indicates amounts rounded to zero (this does not apply when amounts are presented to one decimal point), or nil amount

‘ ’ (a space) indicates data are not available, or not applicable

2.3 Conversions

1 kilogram (kg) = 1,000 grams (g)

2.4 Revisions to data

Data for the latest financial year may be revised in due course. It is the authors’ standard practice to incorporate revisions for previous years into the latest release. Corrections and revisions follow the Home Office corporate revisions policy: Statement of compliance with code of practice for official statistics, page 6.

Each release contains the most up-to-date figures; therefore, each subsequent release supersedes the previous one.

3. Coverage, drugs counting rules and conversion factors

3.1 Misuse of Drugs Act

The statistics in this bulletin and accompanying tables relate to the seizure of drugs controlled under the MDA 1971, which came into force on 1 July 1973, and substances controlled under the Psychoactive Substances Act (PSA) 2016, which came into force on 26 May 2016. The MDA divides drugs into three categories according to their harmfulness to the individual who misuses them, and to society. A full list of drugs in each category is given in Schedule 2 to the MDA 1971, as amended by Orders in Council.

The Home Office first collated drug seizure statistics in an electronic format in 1974. Until the publication in 2006, data originally covered the United Kingdom rather than England and Wales. Since the introduction of the MDA, there have been various changes to which drugs are covered and to recording practices by police forces and other agencies. As such, drug seizure statistics are not directly comparable from year to year and furthermore are not a measure of drug prevalence in society.

3.2 Classification of drugs

The MDA divides drugs into three categories – Classes A, B and C – according to the harm they cause to the user or to society when they are misused. Class A drugs are considered the most harmful. It is not feasible to publish detailed seizure statistics for every drug covered by the MDA. While all drugs are included in the totals, only those in the table below are covered in detail within this release.

List 3: Drugs and their classifications under the MDA

Class A
Cocaine
Crack
Ecstasy
Heroin
LSD
Methadone
Morphine

Class B
Amphetamines*
Barbiturates**
Cannabis*
Ketamine***
Mephedrone

Class C
Anabolic steroids
Benzodiazepines
GHB
Temazepam

Notes:
* Amphetamines and barbiturates are Class A drugs if prepared for injection.
** Cannabis was reclassified from a Class B to a Class C drug in January 2004, and then classified back to a Class B drug on 26 January 2009.
*** Ketamine was reclassified from a Class C to a Class B drug on 10 June 2014.

3.3 Key changes in coverage

Date: 1 July 2003
Change: GHB was classified as a Class C drug.

Date: 29 January 2004
Change: Reclassification of cannabis from a Class B to a Class C drug under the Criminal Justice Act 2003.

Date: 18 July 2005
Change: Raw magic mushrooms were classified as a Class A drug. Previously only prepared (such as dried or stewed) magic mushrooms were classified as Class A drugs.

Date: 1 January 2006
Change: Ketamine classified as a Class C drug.

Date: 18 January 2007
Change: Methamphetamine (commonly known as ‘Crystal Meth’) was reclassified from a Class B to a Class A drug.

Date: 26 January 2009
Change: Cannabis was reclassified from a Class C to a Class B drug.

Date: 23 December 2009
Change: Gamma-Butyrolactone (GBL), 1, 4 – Butanediol, Oripavine and Benzylpiperazine (BZP) became Class C controlled drugs.

Date: 16 April 2010
Change: Mephedrone became a controlled drug (Class B). Other cathinone-based substances also became Class B controlled drugs, though some were already controlled as Class C drugs.

Date: 28 March 2011
Change: Tapentadol (Class A) and amineptine (Class C) became controlled drugs.

Date: 13 January 2012
Change: Phenazepam (Class C) and pipradrol-related compounds (Class B) became controlled drugs.

Date: 10 June 2014
Change: Ketamine was reclassified as a Class B drug.

Date: 26 May 2016
Change: Psychoactive Substances Act (PSA) 2016 is introduced.

Date: 2 December 2016
Change: ‘Third generation’ of synthetic cannabinoids were brought under control as Class B drugs.

Date: 1 April 2019
Change: Pregabalin and Gabapentin were brought under control as Class C drugs.

3.4 Psychoactive Substances Act 2016

Seizures of NPS have been included in the releases for years ending March 2018 to 2021. Due to the large number of different NPS in existence, it is not feasible to report on all individual NPS substances. They have therefore been grouped into four main categories – nitrous oxide, synthetic cannabinoids, NPS powder, and other NPS (including pills). Synthetic cannabinoids are also counted against ‘Other Class B’ seizures, given that the ‘third generation’ of synthetic cannabinoids were controlled as Class B drugs in December 2016.

3.5 Drugs counting rules

A single seizure is where only one drug is seized on a particular occasion (e.g. cocaine).

A multiple seizure is where two or more drug types (e.g. heroin and cocaine) are seized on a particular occasion. The occasion is counted once in the total number of seizures, but a seizure is counted against each individual drug type and drug class involved.

Example: A seizure is made of cocaine, cannabis resin and herbal cannabis. This seizure would be counted as:

• total seizures: one seizure in the overall total for the number of seizures by that agency
• drug type: one seizure of cocaine, one seizure of cannabis resin, one seizure of herbal cannabis and one overall seizure of cannabis
• drug class: one seizure of Class A and one seizure of Class C

Seizures from joint operations involving Border Force and the police are recorded against the lead agency that takes possession of the seized drugs.

3.6 Purity of seized substances

Prior to the year ending March 2012, the National Statistics on drug seizures were supplemented with data provided by the Forensic Science Service (FSS) on the purity of drugs seized (these data were not National Statistics). Data for the year ending March 2012 onwards are not available due to the managed closure of the FSS.

UK Focal Point on Drugs collects and publishes purity data for reports by EMCDDA and the United Nations Office on Drugs and Crime (UNODC).

3.7 Coverage by agency

Seizures from joint operations involving Border Force and the police are recorded against the lead agency that takes possession of the seized drugs.

3.7.1 Border Force

UKBA was launched in April 2008, creating a new frontline operation formed of the Borders and Immigration Agency, UK Visas, and staff from Her Majesty’s Revenue and Customs (HMRC) employed at the frontier. As well as retaining responsibility for the inland control of illicit goods such as cigarettes, tobacco and alcohol, HMRC officers retained the legal power to seize drugs if discovered while they are conducting their inland duties. Consequently, for the years up to and including year ending March 2011, data for UKBA included a few drug seizures possibly attributed to HMRC.

Following the publication of the Vine Report (February 2012) which investigated unauthorised border checks (investigation into border security checks), the Home Secretary split the Border Force and UKBA into separate organisations. This came into effect from 1 March 2012. From the year ending March 2013 edition, the Home Office’s statistical bulletin on the Seizures of drugs in England and Wales refers to Border Force seizures rather than UKBA.

For the year ending March 2012 onwards, UKBA / Border Force figures include seizures made offshore, and which have been attributed to the nearest port (within England or Wales only) on their recording system. These include only those seizures made by its fleet of ongoing sea-going patrol vessels (cutters) that operate around the UK coastline; seizures made overseas by juxtaposed controls are excluded. For the years ending March up to and including 2011, seizures made by cutters were excluded.

Home Office officials and analysts work closely together with Border Force to ensure that its statistics fully comply with the Code of Practice for Official Statistics. A breakdown of Border Force figures contained in Seizures of drugs in England and Wales are published each quarter, within its quarterly compilation of performance information. The drug seizure figures are based on the same counting rules used to compile Seizures of drugs in England and Wales, and quarterly figures relating to Border Force seizures in England, Wales, Scotland and Northern Ireland are presented separately.

3.7.2 Serious Organised Crime Agency (SOCA) and National Crime Agency (NCA)

Seizures by SOCA have not been identified separately in this report because most of its domestic seizures are made with local police forces, with the seizure attributed to the police. It should be noted that many SOCA seizures are attributed to local police forces when operations have been run together.

In October 2013, the NCA was established, replacing many of the functions (including drug seizures) of SOCA.

3.8 Conversion factors

The quantities of drugs seized are summarised in terms of kilograms, doses or plants (for cannabis plants only). Most drugs can plausibly be seized in a preparation form other than kilograms or doses. Therefore, in order to present all seized quantities within a given drug type in terms of one comparable unit (either kilograms or doses), conversion factors are applied to estimate the overall quantity of drugs seized.

Conversion factors were revised from the 2005 publication to reflect trends in average drug preparations. These have been used for annual Seizures of drugs in England and Wales publications since year ending March 2007. All revisions to quantities, conversion factors and units for presentation were made on the advice of the FSS.

For the Border Force’s data in Summary Tables 3b and 3c, and Supplementary Table 2, quantities requiring conversion are not included in the breakdowns, although they are included in the total estimated quantity (kilograms or doses).

Conversion factors have not been updated since 2005 due to closure of the FSS in 2012. The testing of seized drugs is now a service provided to the police by several private companies, rather than one organisation – a process that began before the closure of the FSS. This means that a single source of seized drug purities is no longer available. Home Office analysts will keep this under review and may seek to update the conversion factors in the future if there is evidence that this is required and there is user demand to do so.

Glossary

Amphetamine– a stimulant drug controlled within Class B of the Misuse of Drugs Act (MDA) 1971.

Anabolic steroids – a drug within Class C of the MDA used to enhance sporting performance and muscle building.

Barbiturates – a highly addictive relaxant drug, controlled within Class B of the MDA.

Benzodiazepines – group of drugs that are minor yet addictive tranquillisers and controlled under Class C of the MDA.

Border Force – responsible for frontline border control operations at air, sea and rail ports in the United Kingdom. In this release, Border Force seizures relate to those found in the land territory of England and Wales only.

Cannabis – a relaxant drug also known as marijuana, controlled within Class B of the MDA.

Cannabis plants – live plants often seized from a cannabis ‘farm’.

Cannabis, herbal – dried leaves and flowers of cannabis plants, usually chopped and dried.

Cannabis resin – cannabis in the form of solid, brown lumps. Often rolled with tobacco and smoked.

Class A, B, C – classification of drugs as listed in part I, II and III of Schedule 2 of the MDA. The classification determines the legal sanction (e.g. maximum sentence) with Class A attracting the most severe and Class C the least.

Cocaine – a powerful, addictive stimulant drug, controlled within Class A of the MDA. Included here is cocaine in powder form, see Crack for further details.

Controlled drug – chemical substances listed in the MDA. Unauthorised possession and supply of these drugs are illegal. Some controlled drugs are used as medicines, and the MDA allows certain authorised people, such as researchers or doctors, to use them in research or prescribe them to patients.

Crack – cocaine in ‘rock’ rather than powder form, controlled within Class A of the MDA.

Drug – when used in this release, it refers to a controlled drug.

Ecstasy – also known as MDMA, an acronym of its chemical name, it is a stimulant drug, controlled within Class A of the MDA.

Fentanyl – a powerful synthetic opioid similar to morphine and a painkiller, controlled within Class A of the MDA.

Financial year – the 12 months ending on 31 March.

Gabapentin – a prescription-only medicine used to treat epilepsy and neuropathic pain, controlled within Class C of the MDA.

GHB – gamma-hydroxybutyrate, an anaesthetic drug, controlled within Class C of the MDA.

Government Office Region (GOR) – the Government Office Regions have been the primary classification for the presentation of regional statistics, although the regional government offices were closed in 2011. There are nine GORs in England: North East; North West; Yorkshire and the Humber; East Midlands; West Midlands; East of England; London; South East; and South West. In this report, analysis by region also includes separate analysis for Wales.

Heroin – a highly addictive drug made from morphine, a relaxant and strong painkiller. Usually injected by users and controlled within Class A of the MDA.

Ketamine – a powerful anaesthetic drug often inhaled, can be hallucinogenic, controlled within Class B of the MDA.

LSD – lysergic acid diethylamide, or ‘acid’, a powerful hallucinogenic drug controlled within Class A of the MDA.

Methadone – a synthetic opiate (i.e. from opium poppies) manufactured for use as a painkiller and as a substitute for heroin in the treatment of heroin addiction, controlled within Class A of the MDA.

Mephedrone – a powerful stimulant (sometimes called ‘meow meow’) and is part of a group of drugs closely related to amphetamines, like speed and ecstasy. Mephedrone is controlled within Class B of the MDA, unless seized in an injection form whereby it is controlled within Class A.

Misuse of Drugs Act (MDA) – 1971 Act that legislates against the unauthorised possession and supply of controlled drugs. Reference to the MDA in this release covers the original Act and subsequent amendments and modifications.

Morphine – an addictive opiate, a relaxant and painkiller, controlled within Class A of MDA.

New psychoactive substances (NPS) – newly available drugs that mimic the effect of existing drugs such as cannabis, ecstasy and powder cocaine. Some NPS are controlled under the MDA, while other NPS are illegal to supply, produce and import under the Psychoactive Substances Act 2016.

Police officers – employees of a police force, who have taken an oath (under the Police Act 1996) to uphold the law.

Population figures – some tables and graphs in this release use population figures to calculate the total number of drug seizures per million population. The population figures used for the year ending March 2015 statistics are mid-2014 population estimates based on the 2011 Census, provided by the Office for National Statistics.

Pregabalin – a prescription-only medicine used to treat epilepsy, neuropathic pain and anxiety, controlled within Class C of the MDA.

Psychoactive substance – any substance intended for human consumption that can produce a psychoactive effect.

Psychoactive Substances Act (PSA) – 2016 Act that created a blanket ban on the production, distribution, sale and supply of psychoactive substances in the United Kingdom for human consumption.

Seizure of drug(s) – a discovery and confiscation of a substance or substances that, after testing, are found to be controlled drugs. Not all drugs included in the seizures have been ‘seized’ in the strictest sense of the word; for example, a member of the public may hand in to the police what appear to be drugs found in the street. These items will be recorded at individual police stations and then destroyed.

Synthetic cannabinoids – a class of NPS designed to replicate a similar effect to cannabis.

Temazepam – minor yet addictive tranquilliser, controlled within Class C of the MDA.

Temporary Class Drug Order (TCDO) – a facility under the MDA to trial a substance as a controlled drug for up to 12 months until a decision is made whether to introduce it substantively.

For more information about these and other controlled drugs, please refer to the Home Office’s Frank website.

Appendix A: Key stages in the production of the statistical release

A. Preparatory work

• Annual Data Requirement (ADR) process (during the 12 months prior to the data period)
  • consultation with forces and stakeholders; all stakeholders complete a questionnaire to justify the retention (or otherwise) of each of their series
  • requests for changes or additions to the ADR considered by the ADR committee (which weighs up the benefits against administrative burden)
  • ADR committee decisions for inclusion in the final ADR for submission for Home Secretary’s approval
• review of IT systems (during the 12 months prior to the data period)
  • incorporate any amendments, additions and/or withdrawals
  • any case for IT work incurring costs to be justified and approved by budget manager
• issue statistical returns, covering letter and notes for guidance to police forces (around the start of the data period)
• agree and pre-announce the provisional date of publication of the statistical bulletin on the Office for National Statistics (ONS) publication hub (around 9 to 12 months prior to publication)
• review content of the statistical bulletin and other regular outputs (around six months prior to publication), then agree findings with stakeholders. Any substantial reduction in content of statistical release would require a consultation with users
• review and update project plan for the new financial year (around six months prior to publication):
  • include all the milestones in this framework, plus deadlines and measures of criticality (e.g. a traffic light system)
  • timings to fit in with staffing levels, pressures and the relative priorities of each series
  • timings also to fit in with National Statistics pre-announced months of publication (with no series to be published later than 12 months after the data period) and policy demands

B. Data input and quality assurance

1. police forces’ submission of returns within deadline
   • data collection section deals with force queries on completion of return, with support from output team where required
   • output team deals with all other queries about notes for guidance, definitions, release practice and recording practice
   • data collection section logs and ensures that returns are correctly input electronically
2. figures for police forces are reviewed to see if data are suitable for publication. If not, or if data cannot be supplied, any data supplied by that force will need to be excluded from the publication, and estimated instead, (see Section 1.3, Imputation of data). This is only done as a last resort, and with the agreement of the respective police force. The drug seizure data collection is part of the ADR, and police forces have a statutory requirement to submit the data requested
3. validation and variation checks, and review of any issues identified, with the forces. These checks are a combination of automated error checks and analytical checks, from forces’ data extracted from the database. They are focussed on the key drugs and quantities seized (for example, all notably large drug seizures are checked with police forces before publication). Prior to 2021, these checks were carried out in EXCEL, using extracts of data from the database, but for the year ending March 2021 report, the checks have been produced automatically, using R code. From the results of these checks, analysts produce summaries of the key issues in the data, for review and discussion with the respective forces
4. receipt and input of revised returns following validation checks, and satisfactory reasons or revisions provided following variation checks
5. data confirmation exercise. Each police force is sent a report containing data in a format similar to the format in the publication. Like the data checks in point (3), these were previously produced in EXCEL, but are now generated using R software, then exported to EXCEL for formatting to improve the quality and consistency of the reports. Forces are then asked to provide written confirmation that they agree with the figures that will be published. This is to reduce further the risk of incorrect figures being released and supports the Home Office in any disagreement with a police force over the figures published for that force
6. receipt and input of revised data where appropriate following the data confirmation exercise
7. production of complete validated dataset following all data being signed off by police forces

C. Preparation for publication

1. prepare detailed publication schedule (at least three months before publication), containing all specific tasks, milestones and staff allocated to them
2. agree and pre-announce finalised day of publication (around one to three months before publication)
3. prepare draft of tables, charts and commentary and circulate to nominated people for quality assurance, two to three weeks before publication. This group appears on the pre-release access list
4. send statistical news release and pre-release access for preparation of web pages
5. circulate the commentary, tables, charts and statistical news release, 24 hours before publication, to a nominated list of people (including ministers and press office) as shown on pre-release access list
6. meet with Home Office colleagues on 24-hour list to discuss content and handling issues
7. publication

D. Follow-up work

• wash-up meeting on process of publication
  • agree actions for next year and lessons learned
  • consider any information that could be sent back to police forces to aid their processes
• published dataset to be used for Parliamentary Questions, Freedom of Information and other enquiries (until following publication)