In 1911, Roy Chadwick began work as Alliott's personal assistant and the firm's draughtsman and in 1918 he was appointed Chief Designer. The first Avro aircraft to be produced in any quantity was the Avro E or Avro 500, first flown in March 1912, of which 18 were manufactured, most for the newly formed RFC. The company also built the world's first aircraft with enclosed crew accommodation in 1912, the monoplane Type F and the biplane Avro Type G in 1912, neither progressing beyond the prototype stage. The Type 500 was developed into the Avro 504, first flown in September 1913. A small number were bought by the War Office before the outbreak of the First World War, and the type saw some front-line service in the early months of the war, but it is best known as a training aircraft, serving in this role until 1933. Production lasted 20 years and totalled 8,340 at several factories: Hamble, Failsworth, Miles Platting and Newton Heath.