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1. Understanding military personnel statistics

There are three main ways to measure the number of military personnel (also known as strength): the total full-time UK Armed Forces, total full-time trained UK Armed Forces, or the total full-time UK Regular Forces.

The total full-time UK Armed Forces is the most comprehensive of the three measures. It comprises trained and untrained members of the UK Regular Forces, Gurkhas, and full-time reserve service personnel (FTRS).

The total full-time trained UK Armed Forces is perhaps the most important measure as this is what the 2015 Strategic Defence and Security Review (2015 SDSR) personnel targets are based on.

The 2015 SDSR targets

The 2015 SDSR indicated that the required number of full-time trained UK Armed Forces personnel by 2020 would be 144,200.

The 2015 SDSR also re-affirmed the Government’s commitment to increase the size of the trained strength of the reserve forces (known as Future Reserves 2020) to 35,060 personnel.

Trained strength (or trade-trained strength in the Army) comprises military personnel who have completed Phase 1 and Phase 2 training:

  • Phase 1 includes all new entry training to provide basic military skills.
  • Phase 2 includes initial individual specialisation, sub-specialisation and technical training following Phase 1 prior to joining the (trade) trained strength.

Changes to trained strength definitions

In June 2016 the Ministry of Defence announced that the Army planned to use Phase 1 trained Regular and Reserve personnel in response to crises within the UK.

From 1 October 2016 Army personnel who completed Phase 1 of training, but not Phase 2, were considered trained. The Royal Navy/Royal Marines and the Royal Air Force (along with their reserve services) were not affected by this change.

Army personnel who have completed Phase 1 and Phase 2 training are called ‘trade-trained’. This population aligns with the old definition of trained personnel and maintains the continuity of statistical time series. Ministry of Defence statistical bulletins continue to show figures on those that are trade trained (except for Army Future Reserves 2020 where trade trained figures are not provided after 1 October 2016.)

The trained strength (Phase 1 and Phase 2) of the Royal Navy/Royal Marines and the Royal Air Force, and the trade-trained strength of the Army (Phase 1 and Phase 2), is what is counted against the annual liabilities and the 2015 SDSR target for 2020. For Future Reserve 2020 targets, Phase 1 trained Army reserve personnel are counted, whereas it is Phase 1 and Phase 2 trained personnel for the Royal Navy/Royal Marine and Royal Air Force reserve.

2. UK Armed Forces

The total strength of the full-time UK Armed Forces (trained and untrained) at 1 January 2021 was just under 156,600. Most personnel were within the Army (56%) with the remainder being equally split between the Royal Navy/Royal Marines and the RAF.

Across all services there were 30,150 officers (19%) and 126,400 personnel with other ranks (81%). The distribution of officers to other ranks varied across each service: a quarter of all RAF personnel were an officer (25%) compared to less than a fifth (17%) in the Army.

2.1 Trained strength

As at 1 January 2021 all branches of the UK Armed Forces were below the 2015 SDSR target for 2020. The full-time trained strength of the UK Armed Forces was 135,444 which is a shortfall of 8,756 (6%). The Army had the largest proportional shortfall (7%) and the Royal Navy/Royal Marines the smallest (4%).

On the 1 January 2021 the required size of trained UK armed forces personnel (those who have completed both phase 1 and 2 of training) was 144,676. The actual size however, as noted above, was 135,444 – a shortfall of 6.4%.

Based on media reports, it is expected that the MoD’s Integrated Review (to be published on 16 March) will suggest a reduction of 12,500 personnel from the Army to size of around 70,000. There is speculation that instead of a redundancy programme (as in the early 2010s), there will be fewer people recruited to replace natural wastage of those leaving the Army each year.

2.2 Operational Pinch Points

The surplus/shortfall in the strength of the full-time trained UK Armed Forces against the requirement is one indicator of the Armed Forces ability to execute military tasks. Other indicators include the surplus/shortfall in key trades or ranks: these are known as Operational Pinch Points (OPPs).

An OPP is when ‘shortfalls in the trained strength of a branch specialisation, sub-specialisation or area of expertise need to be mitigated to prevent a measurable, detrimental impact on current, planned or contingent operations’.

The latest Ministry of Defence annual report shows that there were 36 OPPs in January 2020 across the Armed Forces. Broken down by service the number of OPPs are:

  • Army: 17, an increase of 10 compared to April 2019 and mainly relate to Communications, Intelligence and Engineering roles.
  • Royal Navy/Royal Marines: 19 (including four from the Royal Fleet Auxiliary, the same as in April 2019 and mainly relate to engineering roles.
  • RAF: A review reduced OPPs to zero, down from 7 in April 2019.

3. UK Regular Forces diversity

Data on the diversity is published twice a year and focuses on the diversity of the UK Regular Forces rather than the wider UK Armed Forces.

3.1 Gender

At 1 October 2020 there were 16,110 women in the UK Regular Forces and accounted for 11% of the total trained and untrained strength.

The proportion of women in the UK Regular Forces has increased over the past few years. At 1 April 1990 women accounted for around 6% of the total UK Regular Forces; by 1 April 2000 this proportion was around 8%. Since 2000 the share of women in the Regular Forces has increased almost every year.

The 2015 SDSR stated that by 2020 at least 15% of the intake to the UK Regular Forces should be female. In the 12 months to 30 September 2020, 11.2% of the total intake was female.

On 8 July 2016 David Cameron (the then Prime Minister) announced that women would be allowed to serve in close combat roles by 2018. This was achieved on the 25 October 2018 when Defence Secretary Gavin Williamson announced that all roles in the military are open to women.

3.2 Ethnicity

As at 1 October 2020 around 9.1% of personnel (13,200) identified as belonging to a non-white ethnic group. The Army had the highest proportion (13.4%), followed by the Royal Navy/Marines (4.8%) and RAF (3%). As with women, the total proportion of non-white ethnic groups personnel across the UK Regular Forces has increased over recent years: on 1 April 2000 around 1% of personnel identified as belonging to a non-white ethnic group.

The 2015 SDSR stated that by 2020 at least 10% of the intake to the UK Regular Forces should be personnel belonging to a non-white ethnic group. In the 12 months to 30 September 2020, 13% of total intake were personnel from a non-white ethnic group.

3.3 Age

At 1 October 2020 25% of UK Regular Forces personnel were under the age of 25. The average age of all Officers was 37, while the average age of all other ranks was 30. The overall average age was 31.

3.4 Religion

At 1 October 2020 64% of UK Regular Forces personnel declared a Christian religion. Around 32% of personnel declared no religion. The next largest religion declared was Hindu (1%) followed by Buddhist (0.7%). Around 0.4% of personnel declared they were Muslim. Other faiths (Druid, Pagan, Rastafarian, Spiritualist, Zoroastrian, Wicca, Baha’i and others) accounted for 0.9%.

4. UK Regular Forces: inflow and outflow

Inflow comprises entrants, re-entrants, direct trained entrants (including professionally qualified officers), transfers to the Army from the Gurkhas and from the reserves. Outflow includes trained and untrained personnel leaving the service, deaths, and recalled reservists on release. It does not include promotions (from other ranks to officers) or flows between services.

Between 2000 and 2020, total inflow and outflow have both decreased over time. Inflow to the UK Regular Forces has decreased from 25,550 in 2000 to 16,344 in 2020 (a 36% reduction) and outflow decreased from 26,620 in 2000 to 15,455 in 2020 (42% reduction). Between 2000 and 2020 inflow has only been higher than outflow for five years.

In the year to 31 December 2020 just under 16,000 entered the UK Regular Forces and around 12,700 left.

5. Reservists

Reservists are civilians who commit to train a set number of days per year and may be mobilised/called into permanent service for a set period (usually no more than 12 months). They may train and deploy alongside Regular Forces on operations in the UK or overseas. Reservists are paid while training and deployed. 

Each of the three services has a reserve element: Army Reserve, Maritime Reserve (comprising the Royal Navy Reserve and Royal Marines Reserve) and the RAF Reserve.

Reservists may also serve in Joint Forces Command, for example in the Joint Cyber Reserve Force.

In addition to the volunteer Reserves are the Regular Reserves: former personnel who retain a liability (obligation) to be called up for service in times of need are known as Regular Reserves.

The terms used for reservists can be confusing although a couple of categories worth mentioning: Mobilised Reservists are Volunteer or Regular Reserves who have been called into permanent service under the Reserve Forces Act 1996. Then there is a separate category of reservists who work full-time for a set period. These are known as Full-Time Reserve Service (FTRS) personnel and are used differently by each service and may have different commitments.  

A glossary of terms used for reservists in the quarterly personnel statistical bulletins is available here

Further information on Armed Forces Reserves, including commentary on Government policy since 2010 and current issues, can be found in a Lords Library briefing paper Armed Forces Reserves.

5.1 Future Reserves 2020

The Future Reserves 2020 (FR2020) refers to the programme begun under the Coalition Government (2010-15) to expand the size of the trained element of the Armed Forces Reserves, increase the circumstances in which they might be deployed, and better integrate the reserves with the regulars.

This policy was driven by the findings of an independent commission into the Reserves in 2011 and encapsulated in a 2013 White Paper ‘Reserves in Future Force 2020: valuable and valued’ 

(Cm 8655). The Defence Reform Act 2014 removed limitations on how the Reserves could be used and changed the name of the Territorial Army to Army Reserve.  

The Ministry of Defence provided revised trained strength targets for the Reserves in November 2016 (HCWS248), revising those announced in December 2013.

The original December 2013 target was based on the number of trained personnel (those who have passed Phase 1 and Phase 2 training). Following the change in definition of the trained strength for the UK Regular Army and Army Reserve in 2016, the measurement/target for the Army Reserve is based on those who have passed Phase 1 only. The Maritime and RAF Reserves targets were unchanged.

The November 2016 statement set the trained strength targets for 31 March 2019 at 35,060 personnel: 30,100 personnel for the Army Reserve, 3,100 personnel for the Maritime Reserve, and 1,860 personnel for the RAF Reserve.

The RAF Reserve is the only element of the FR2020 to have acheived its targeted strength. The Maritime Reserve is close to achieving its target – by 1 January 2021 it was shy of its 3,100 target by 256 personnel. The Army Reserve is current missing its target by 3,180 personnel; this is despite the change in the trained strength measurement/target which occurred in October 2016. Overall the trained strength of personnel within the FR2020 programme at 1 January 2021 was 33,000 – this is a deficit of 2,414 against the target.

6. Location of personnel

The Ministry of Defence publish annual data on the stationed location of trained and untrained UK Regular Forces personnel.

As at 1 April 2020 most personnel were stationed in the United Kingdom (around 96%). Of the 10,500 personnel stationed overseas the majority were in Europe (63%), followed by North America (16%) and North Africa and the Middle East (8%). Around 13% of personnel were stationed elsewhere in the world.

Within Europe (excluding the United Kingdom) most personnel were in Cyprus (2,290) and Germany (540). Around 1,000 personnel were stationed across Belgium, Gibraltar, Italy, the Netherlands, Portugal, Norway, France and the Czech Republic.

Following the 2010 Strategic Defence and Security Review there has been a withdrawal of the UK’s personnel presence from Germany (a reduction of 15,500) with the aim to completely remove personnel by 2020.

As at 1 April 2020 of those personnel stationed in the United Kingdom the large majority were in England (90%), 7% were stationed in Scotland, 2% were in Wales and 1% were in Northern Ireland.


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