Marshall Aerospace and Defence Group is an aircraft maintenance, modification and design company located at Cambridge Airport, which it also owns and operates. Formerly known as Marshall's of Cambridge, it was originally founded by David Gregory Marshall in 1909. Initially operating chauffeur services, the firm soon branched out into vehicle repair and dealership activities. During the 1930s, Marshall's became increasingly engaged in aviation; by the end of the Second World War, the company had trained in excess of 20,000 aircrew for service within the Royal Air Force. It was also engaged repair and modification of military aircraft during the conflict; it has been claimed that Marshall's performed work on over 5,000 aircraft.