William was the third child of William and Maggie Stephen, born on the 24th. March 1924 in Banffshire, Scotland. Shortly afterwards the family moved south to Old Romney, Kent where his father gained the position of bailiff at Sycamore Farm.

Having attended school locally, William volunteered for the Royal Air Force as soon as he came of age. He passed suitable for flying duties, was trained as an air gunner and then posted to 101 Squadron at Ludford Magna.

He joined a specialist unit which flew Lancasters that contained radio jamming equipment. Their role was to fly as part of the bomber stream and an eighth member of the crew operated the equipment to disrupt those enemy transmissions that were guiding night fighters towards their targets.

On the afternoon of 20th January 1944, the RAF sent a force of 769 planes to attack Berlin. The Luftwaffe used the Zahme Sau (Tame Boar) tactic: when the alert was ordered, the fighters took off and circled radar beacons until the raiding bomber stream was tracked; they were then directed towards the targets. 

The bomber stream was detected some 100 miles off the Dutch coast as it moved towards Kiel, possibly by the radar ship 'Togo'. At this stage the skies were clear and a night fighter attacked Lancaster Mark III, LM417 over Bitterfeld.

Sergeant John Stephen and fellow gunner Sergeant George James were killed. Although severely damaged the aircraft managed to return to Ludford Magna and the remains of the deceased returned to their families.