First successful British model of self-propelled artillery. It was armed with an 18 pdr (83.8 mm) gun on a Vickers medium tank chassis.
The cannon could be used against both ground and aerial targets. The Birch gun was tested as part of the Experimental Mechanized Force (EMF) in the 1920s. The Force undertook various experiments in mechanized warfare combining tanks and infantry with their own motorised transport.