The Charlton Automatic Rifle was to act as a substitute for what First World War-era light machine gun of US design?
Lewis gun The Lewis gun (or Lewis automatic machine gun or Lewis automatic rifle) is a First World War-era light machine gun of US design that was perfected and mass-produced in the United Kingdom, and widely used by British and British Empire troops during the war. With its distinctive barrel cooling shroud and top-mounted pan magazine, the Lewis served to the end of the Korean War. It was also widely used as an aircraft machine gun, almost always with the cooling shroud removed, during both world wars.
Vickers machine gun The Vickers machine gun or Vickers gun is a name primarily used to refer to the water-cooled .303 British (7.7 mm) machine gun produced by Vickers Limited, originally for the British Army. The machine gun typically required a six to eight-man team to operate: one fired, one fed the ammunition, the rest helped to carry the weapon, its ammunition, and spare parts. It was in service from before the First World War until the 1960s, with air-cooled versions of it on many Allied World War I fighter aircraft.