What is the Size of the British Armed Forces since 1700?

I have always been interested to know how the size of the British armed forces has fluctuated over the years, and the statistics in a FOI request from the Ministry of Defence (MOD) makes interesting reading.

From 1700 to 1900, as you might expect, the figures are imprecise estimates, and pretty much apply only to the Army. It is important to note that the figures apply to Regular forces only and have been rounded to the nearest 1,000.

If you know your history, you can understand the expansion and contraction of the numbers of personnel in response to events. Naval personnel numbers slowly, but inexorably, increase between 1700 and 1918, reaching 450,000 and dropping to 136,000 by 1920.

By 1918, there are an estimated 4.5 million personnel in the British armed forces. This is only exceeded in 1944 and 1945 with approximately 4.7 million and 4.9 million respectively – dropping sharply to 1.9 million by 1946.

The breakdown of personnel by Service is also interesting. For example, of the estimated 4.7 million personnel in 1944 approximately:

  • 864,000 were in the Royal Navy.
  • 2.742,000 were in the British Army.
  • 1,085,000 were in the Royal Air Force.

This is in contrast to 1918 when the breakdown of the estimated 4.6 million was approximately:

  • 450,000 in the Royal Navy.
  • 3,838,000 in the British Army.
  • 295,000 in the Royal Air Force.

Once we move into the Cold War era, the British armed forces witness a slow decline over the decades.

By 2016, Defence Statistics suggest the Regular British armed forces numbered 151,000 personnel:

  • 85,000 of which formed the British Army; has not been below that number since 1836.
  • 33,000 of which formed the Royal Navy; has not been below that number since 1835.


FOI 2017/04440 dated 28 April 2017.


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