Alan left school in 1942, a year early to join up at start of 1943.  He did an Engineering Qualification and joined the Royal Engineers, 3 Para Squadron, 6th Airborne. 

He was parachute jump trained at RAF Ringway on Course 68. This course ran between 14 and 27 June 1943. 

He was a member of 2 Troop, 7 Section and saw action in the invasion of Normandy, June 1944.

As such his letters show the progression from School to the Army and then to Normandy on the 6 June and onward to Germany then Asia. A transcript of his letters can be seen here.