An older type of .303 calibre Lewis machine gun - early 1920's.
Notice the bag to catch the spent cartridges.
The Vickers gas-operated machine gun, or commonly known as the 'K' Gun.
The .303 calibre Bren Gun, a favourite weapon amongst the forces.
A 20mm Oerlikon gun replacing all other machine guns.
This is on HMs/m TRENCHANT.