This guide provides quality and methods information for our UK armed forces veterans, England and Wales bulletin.

We produce annual statistics on those who have served in the UK armed forces in England and Wales. This includes people aged 16 years and over who have previously served in the regular or reserve UK armed forces.

The characteristics we compared include geographical areas (with the lowest level area being local authority), age, sex and, from the 2025 data onwards, a regular and reserve breakdown. We have produced these by linking veteran information from Census 2021 and the Ministry of Defence's (MOD's) Service Leavers Database (SLD) into our population database. More information on the data linkage process is available in Section 5: How we produce the statistics.

There is a strong user need for producing ongoing veteran statistics, as this meets the needs of service providers and others who support veterans in line with the Armed Forces Covenant. This covenant is a promise by the nation, ensuring that those who serve or who have served in the armed forces, and their families, are treated fairly.

These are official statistics in development. The only accredited official statistics currently available for veterans are from Census 2021 (see our UK armed forces veterans, England and Wales: Census 2021 bulletin). For more detail on this designation, see Section 6: Quality of the statistics.

We updated this guide on 13 October 2026. Some of the important changes we made to quality and methods since the release of our UK armed forces veteran statistics for England and Wales, research update: 2023 article, published in August 2025, are:

• the inclusion of a regular and reserve veteran breakdown in the 2025 veteran statistics; this breakdown is not available for the 2024 statistics because the required method was not available for the 2024 data

• from 2025 onwards, Service Leavers Database (SLD) records in which the person is a university cadet, other, or with a missing service type, are classified as "did not previously serve in the UK armed forces"; this change aligns the statistics with the Harmonised standard for previous UK armed forces service definition of a veteran and may affect comparability with previous years

• the process used to produce the Statistical Population Dataset (SPD) was updated from version 5.1 to version 6.0, with changes to improve reproducibility and the use of de-identified data

For more information on latest, past and upcoming changes, see Section 7: Changes and their effects on comparability over time.

We present statistics on UK armed forces veterans for England and Wales in our UK armed forces veterans - England and Wales dataset.

The estimates for 2025 are summarised in our UK armed forces veterans, England and Wales: 2024 and 2025 bulletin.

Breakdowns in the datasets

These statistics include breakdowns of the veteran population in England and Wales by:

• source (Census 2021 and the Service Leavers Database (SLD))

• country

• local authority

• age

• sex

• whether veterans served in the regular or reserve forces (this is only in the 2025 data)

Time periods covered by these statistics

Census 2021 provides data on people who were veterans as of Census Day, 21 March 2021, while the SLD covers veterans who have left the UK armed forces at any time since 1975 and who are not currently serving. For example, the 2025 SLD extract includes veterans who were not currently serving on 30 June 2025. Therefore, the SLD provides more up-to-date information on service leavers but may not include older UK armed forces veterans who left service before 1975.

Veterans who left service before 1975 but who moved to live in England and Wales after Census Day 2021 may be included as part of the usual resident population (see Section 10: Definitions) on the Statistical Population Dataset (SPD), but would not be recorded as veterans. This is because the SLD would not record their service and they would not have responded to the Census 2021 question on UK armed forces service in England and Wales.

Geographic boundaries

These veterans statistics are presented geographically by country and local authority in England and Wales, using the standard area names and Government Statistical Service (GSS) codes.

What the statistics exclude

• Lower geographic detail because of disclosure control requirements.

• Regular and reserve splits for years before 2025.

• From 2025 onwards, records classified in the SLD as university cadet, other, or missing service type from the "did not previously serve in the UK armed forces population" category, to align the statistics with the Harmonised standard for previous UK armed forces service.

• Further demographic breakdowns of the data.

To produce statistics on the veteran population, we use two sources of data on people's veteran status:

• Census 2021

• the Ministry of Defence's (MOD's) Service Leavers Database (SLD)

These two sources are used because Census 2021 provides information on people who indicated that they had been veterans as at Census Day, 21 March 2021, while the SLD contains information on personnel who have left the UK armed forces since 1975 and who are not currently serving.

Using both sources enables us to include veterans who left service before 1975, who are not covered by the SLD, and veterans who left service after Census Day, who are not covered by Census 2021. Veterans from these sources are linked to the Statistical Population Dataset (SPD), which provides the population base (see Section 10: Definitions) used to produce the statistics.

The SPD allows migrants who arrived in England and Wales since Census Day 2021 to be included, and people who have emigrated or died since 2021 to be removed. This means that veterans who have died or emigrated since Census 2021 are removed from the population base.

The data used to create the SPD do not include veteran status. As a result, some veterans who have moved to England and Wales since Census 2021 may not be linked, particularly if they left service before 1975 and are not covered by the SLD.

Census 2021

For the first time, Census 2021 included a question asking people aged 16 years and over whether they had previously served in the regular UK armed forces, reserve UK armed forces, or both, as of Census Day, 21 March 2021.

Service Leavers Database

The SLD provides information on personnel who have left the UK armed forces since 1975 and who are not currently serving. The SLD is sourced from legacy personnel systems and the current system, Joint Personnel Administration (JPA).

To produce the veterans statistics, we use administrative data sources. The main stages of the process are:

• the Ministry of Defence (MOD) supplies their Service Leavers Database (SLD) to the Office for National Statistics (ONS)

• we clean, deduplicate and deidentify the SLD before using it in our analysis

• we link the SLD to the Demographic Index (DI) (see Section 10: Definitions) using NHS numbers

• census records with imputation are classed as "missing"

• census records are linked to the DI using ONS identifiers; only records with a clear one-to-one match are retained, and the linked data are deduplicated on ONS identifiers

• we then link the DI to the population base (those aged 16 years and over in version 6.0 of the Statistical Population Dataset), to allow production of data on the usual resident veteran population in England and Wales

Figure 1 shows the linkage process for the census and the SLD to produce the veterans statistics.

Figure 1

Source: Ministry of Defence and the Office for National Statistics

Download this image Figure 1

.png (27.7 kB)

The Census 2021 veterans question asked respondents to indicate whether they had previously been in the Regular Armed Forces, the Reserved Armed Forces, or both.

For SLD veterans, regular and reserve status was derived using "service type" information and the MOD's "ever been regular" flag to link people who had served as a regular, a reserve, or both. Where veterans are present in both sources, the SLD classification was prioritised, as it provides more up-to-date information for those who left service after Census Day, 21 March 2021, and is based on administrative records rather than self-reported data.

Statistical designation

These statistics are labelled as official statistics in development. They are based on information from Census 2021 and the Service Leavers Database (SLD). We are developing how we collect the data and produce the statistics to improve their quality.

Once we have completed these developments, we will review the statistics with the Statistics Head of Profession.

If the statistics meet trustworthiness, quality and value standards based on user feedback, we will remove the "official statistics in development" label to publish under the "official statistics" label.

If they do not meet trustworthiness, quality and value standards, we will consider approaches for further development, but there is also the possibility that we stop producing them.

We will inform users of the outcome of our review and any changes, and any from the Office for Statistics Regulation (OSR).

How we quality assure the data and statistics

1. Once the data have been produced, we recreate the analysis to ensure the same figures can be reproduced independently.

2. For each year, we quality assure (QA) the asset build and linkage analysis stages, as well as the source data and coverage analysis stages.

3. For 2025 onwards, we also QA the regular and reserve breakdowns.

4. We review trends and patterns in the data, investigate any unexpected results, and review information provided by data suppliers to ensure the data are being used and reported appropriately.

5. We align with the Harmonised standard for previous UK armed forces service by using a consistent definition of veterans in this analysis.

The Statistical Population Dataset (SPD) and Demographic Index (DI) continue to be assessed and developed across the Office for National Statistics (ONS). Ongoing work aims to improve understanding of their quality, strengths and limitations, and their suitability for different uses. Further information is available in our Assessment of criteria for moving to admin-based population estimates as official estimates of population, England and Wales: 2026 article.

Quality information on the Census 2021 veterans estimates can be found in our UK armed forces veterans quality information for Census 2021 methodology.

Strengths and limitations

Strengths

• Using Census 2021 and the SLD together allows us to produce veteran population statistics for England and Wales using administrative data.

• Census 2021 provides accredited coverage of veterans who left service before 1975, including older UK armed forces veterans who are not in the SLD.

• The SLD enables the inclusion of veterans who left service after Census Day, 21 March 2021.

• Using both sources together allows Census 2021 data to be effectively rolled forward by using the SLD, accounting for changes in the veteran population over time through the inclusion of newer service leavers.

• SPD data are produced for each year and aim to reflect the usual resident population for the year ending 30 June; the administrative data used in SPDs help ensure that people who have died, or who have left England and Wales since Census 2021, are not included in the veteran population estimates.

Limitations

Undercoverage

• Undercoverage may occur because some veterans are not included in the population base (see Section 10: Definitions); this can happen if they are not in the administrative data sources used to create the population base, or if records cannot be linked successfully.

• Undercoverage may also occur where veteran information cannot be linked successfully to the population base; this may arise because of non-response to the Census 2021 veterans question or unsuccessful data linkage.

• The derived regular and reserve service categories from SLD records are subject to some limitations; service type reflects a veteran's status at the end of their service, as the MOD does not currently provide an "ever been reserve" indicator, and changes between service type are not always reflected in historic data.

• Consequently, some veterans who have served in both the regular and reserve forces may be classified as regular only or reserve only, resulting in an undercount of veterans included as having served in both.

• The coverage of NHS numbers on the SLD is poorer for older records, particularly records from before NHS numbers became routinely recorded within Defence Medical Systems, in 2013; while this means that linkage rates are lower for older SLD records, these veterans will have mostly been included in Census 2021 data.

Overcoverage

• Overcoverage may occur when people are incorrectly indicated as veterans, including cases where a person who indicated that they were a veteran in Census 2021 has since returned to active service but is still flagged as a veteran.

Other limitations

• The linkage does not include the split between regular and reserve veterans for any datasets before 2025.

• The design of the SPD relies on evidence of activity or interactions in administrative data; it does not contain information on whether any international migrants to England and Wales since Census Day, 21 March 2021, or people who moved to England and Wales from Northern Ireland or Scotland, were UK armed forces veterans. 

European Statistical System Quality Dimensions

The Office for National Statistics (ONS) has developed Guidelines for measuring statistical quality based on the five European Statistical System (ESS) Quality Dimensions. These are:

• relevance

• accuracy and reliability

• timeliness and punctuality

• comparability and coherence

• accessibility and clarity

We have integrated these considerations into this guide.

Latest changes

We previously published our UK Armed forces veteran statistics for England and Wales, research update: 2023 article. As of 2026, we intend to produce annual statistics on the veteran population of England and Wales based on this quality and methods guide.

Changes to the Statistical Population Dataset

To produce version 6.0 of the Statistical Population Dataset (SPD), we updated the process to improve reproducibility and the use of de-identified data. This means that comparisons between our 2023 research update and these statistics should be made with caution.

Inclusion of regular and reserve breakdowns

Compared with 2024, there is also a difference in the 2025 veteran statistics, specifically the addition of the regular and reserve breakdowns. As part of this change, those included in the Service Leavers Database (SLD) as a university cadet, other, or missing are now classified as "did not previously serve in the UK armed forces", in line with the Harmonised standard for previous UK armed forces service. This may result in further differences between our 2025 statistics and our 2023 and 2024 datasets. 

Past changes

There have been no other notable changes to the quality or methods since we started producing these statistics.

Upcoming changes

We will explore the feasibility of including further demographic and service-related breakdowns.

Future developments

More detailed geographic information and some breakdowns for small population groups may not be possible because of statistical disclosure and confidentiality requirements.

We will also explore potential methods to reduce undercoverage in the population base and where veteran information cannot be linked.

Scottish Government

The Scottish Government's supply of veteran statistics is not comparable with ours. This is because of the following differences:

• our statistics represent the veteran population of England and Wales, while the Scottish Government's statistics represent the veteran population of Scotland only

• we produce annual veteran population estimates, while Scottish Government statistics are based on a single reference period (Scottish Census 2022, 20 March 2022)

• our estimates use administrative data, combining veteran information from Census 2021 and the Service Leavers Database (SLD) with the population base; Scottish Government statistics use survey data from their Census 2022 only

• Scottish Government statistics include additional demographic breakdowns beyond those presented in our statistics

Northern Ireland Statistics and Research Agency

The Northern Ireland Statistics and Research Agency's (NISRA's) Census 2021-based and SLD supply of veteran statistics is not comparable with ours. This is because of the following differences:

• our statistics represent the veteran population of England and Wales, while NISRA statistics represent the veteran population of Northern Ireland only

• we produce annual veteran population estimates, while NISRA statistics are based on a single reference period (Census 2021, 21 March 2021)

• NISRA statistics include additional demographic breakdowns beyond those presented in our statistics

A range of organisations and government departments use these UK armed forces veterans statistics to support their understanding of the veteran population, inform policy development, and provide evidence for decision-making. These include:

• the Office for Veterans' Affairs (OVA)

• the Royal British Legion (RBL)

Other users include local authorities, academics, researchers, charities, and other organisations with an interest in the veteran population.

Demographic Index

The Demographic Index (DI), derived from administrative data, is a record of people who have lived in England and Wales for some or all of the time since 2016, although some data go back to 2011. Each person within the DI has a unique "ONS ID" that can be used for linking. The index itself is not available to the public, so personal data are protected. These data are used to help securely link other de-identified datasets together for analysis.

Population base

Our population base for these statistics is the 2024 and 2025 Statistical Population Dataset version 6.0 (SPD V6.0) for England and Wales, filtered to those aged 16 years and over.

Statistical Population Dataset

A Statistical Population Dataset (SPD) is a dataset that includes the usually resident population, on a reference date (30 June) for a given year within England and Wales. It is constructed from administrative sources that are linked together, and the combined evidence is used to derive who is usually resident and their characteristics of age, sex and geographic location.

UK armed forces veterans

People who have previously served in the UK armed forces. This includes those who have served for at least one day in the UK armed forces, either as regulars, reserves, or merchant mariners who have seen duty on legally defined military operations. Further information is provided in the Harmonised standard for previous UK armed forces service.

Usually resident population

This is the standard, United Nations definition outlined in their Principles and Recommendations for Population and Housing Censuses (PDF, 3.76MB). It includes only people who reside in a country for 12 months or more, making them usually resident in that country. Visitors and short-term migrants are excluded.