William Watt Allan was the son of John William Allan and Annie Ellen (Watt) Allan, of Newcastle-on-Tyne. Husband of Rose Lilian (Reading) Allan. Married April 1943. He enlisted in the Royal Army Medical Corps, attached Royal Engineers, and volunteered for Airborne Forces.

William successfully completed parachute training and was posted to B Squadron, Special Air Service Regiment, Army Air Corps.

He was murdered by a Nazi firing squad on 7 July 1944, aged 29 and is now buried in Rom Communal Cemetery, Southern France.