Because of his age at the onset of the Second World War, the troops affectionately called him "Pop".

[2] In World War II Green enlisted in the RAF at the rank of Flight Lieutenant.

He was 52 years old when he signed up with the RAF's Bomber Command: he was shot down on his first mission over Denmark in July 1940.

The prisoners escaped Stalag Luft III by methodically digging a tunnel.

Of the 76 who escaped, 3 men got away, 50 were executed, and of the officers remaining the majority were returned to Stalag Luft III whilst some were taken to other places, like Sachsenhausen.