John Williamson volunteered for the airborne forces having previously served with The Yorks and Lancs Regiment. He was successfully parachute jump trained at RAF Ringway on Course 119. This course ran between 3 and 22 June 1944. His instructor noted this about John's performance:

"Average, confident, cheerful, good leader"

This course was for men being sent to Normandy as reinforcements. John was then posted to The 12th Battalion The Parachute Regiment.

He was captured near Caen 18 August 1944 and interned at Stalag IV. His POW number was 87529. 

John joined the Reserves 11 May 1946.