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Anti-aircraft gun at the Level, 1947

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Two years after the end of WW2, an anti-aircraft gun was shown off in a Brighton park. Collections Assistant Charles Paddick looks at the story behind the gun.

This photograph was taken by the Brighton and Hove Herald newspaper at an army exhibition called ‘Salvo’. The exhibition was held on 27 September 1947 at the Level in Brighton.

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In the centre of the photograph is a mounted anti-aircraft gun known as an Ordnance QF 3.7-Inch. Anti-aircraft guns were designed to fire at airborne targets from ground level.

What’s in a name?

The meaning of the gun’s name can be broken down into several parts:

  • Ordnance applies to weapons designed for the propulsion of missiles by explosive force.
  • QF stands for Quick Firing. It denotes that the ammunition is made to facilitate rapid loading with the means of ignition, propellant charge, projectile and fuse being joined together to form one fixed complete round which can be loaded in one motion.
  • 3.7-inch refers to the calibre of the gun, which is the measurement of the diameter of the bore shell or bullet.

Who is operating the gun?

In the photograph the gun is crewed by a detachment of seven men from the 411(Sussex) Coast Regiment, Royal Artillery (Territorial Army), which was headquartered at nearby Preston Barracks and formed part of the 101 Coast Brigade.

An anti-aircraft brigade was made up of Anti Aircraft regiments. Each regiment typically had three batteries, each containing eight guns in two troops of four.

Pre-war background and development

During WW1 anti-aircraft gunnery were developed to meet the growing threat of air attacks on the United Kingdom and the Western Front. In 1914 the War Office issued a specification to modify the Vickers naval 3-inch Q.F. gun for an anti-aircraft role. This role lead to the development of the QF 3-inch 20 CWT.

The guns where operated by the Royal Garrison Artillery and remained in service with the Royal Artillery on its amalgamation after the end of the First World War. In 1925 the Textbook of Anti-Aircraft Gunnery Volume 1 was published, in which recommendations were made for heavy anti aircraft guns. A few years later in 1928 a Royal Artillery Committee minute lead to new designs and experiments, with a General Service Specification being laid out in 1933.

The specification for the new heavy anti-aircraft gun was that ii had to fire a 28lb shell; have a 3.7-inch bore; a 3,000 feet per second muzzle velocity; a 35,000 feet ceiling; the ability to be towed on roads at a speed of 25 mph; have a maximum weight of eight tons; and an into action time of 15 minutes in order to be better able to engage high speed and high flying aircraft.

The following year Vickers-Armstrong Ltd came up with a pilot gun, which passed proof in 1936. Production of the Ordnance QF 3.7-Inch AA was authorised in 1937 and manufacture began in 1938.

The gun was used during WW2 and remained in service by the British Army until 1959.

Firing the gun

The firing process required several complex movements, yet a trained crew could maintain a rapid rate of fire. British Movietone has some excellent footage of an Ordnance Q.F. 3.7-Inch being fired which is well worth a watch:

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The guns were operated alongside a height finder and predictor, which allowed the guns to fire at the correct distance and altitude to disrupt an enemy aircraft’s flight path. The information was fed to the Ordnance QF 3.7-Inch electronically.

Charles Paddick, Collections Assistant