the company turned to producing munitions and war materiel during the First World War. In addition to shells, it manufactured aero-engines and whole aircraft, including the Royal Aircraft Factory F.E.2 fighter and bomber. By the end of the conflict, in excess of 1,100 aircraft had been completed by the firm.

In 1930 the company acquired Contraflo Condenser & Kinetic Air Pump Co, Westminster, in 1933 A. G. Mumford,