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–Berthier The Vickers–Berthier (VB) light machine gun manufactured by Vickers-Armstrong was based on a French design of just before World War I intended for use on aircraft. In 1925 Vickers in Britain purchased licence rights for production in their Crayford factory, and as a replacement for the Lewis Gun. It was an alternative to the water-cooled Vickers machine gun of same manufacture. The weapon used a similar gas and tipping bolt mechanism to the Bren gun, and also had a removable barrel, and was air-cooled like the Bren. It was adopted by the Indian Army in 1933.