Heart of Oak reads the school motto at Forest School, Snaresbrook. A former pupil, Battle of Britain fighter pilot, Squadron Leader Geoffrey Wellum (DFC), has certainly lived up to the name.

Born in Walthamstow on August 4, 1921, Geoffrey joined the RAF on a short-service commission straight from school aged only 17. He went on to serve with the famous 92 Squadron throughout the Battle of Britain.

Now the 89-year-old’s memoirs have been turned into a film titled First Light, which opens a series of BBC programmes marking the 70th anniversary of the Battle of Britain next week. The film highlights the dedication of everyone on the ground who built and maintained the aircraft, as well as the camaraderie between squadron members.

As a young boy, Geoffrey admired the bright livery of airplanes flying over North Weald. He loved everything to do with aircraft and enthusiastically constructed model planes. His passion for flying remains undimmed but the conflict took its toll.

“I didn’t talk about it,” recalls Geoffrey. “It was all locked in the back of my brain, but then eight years ago I wrote the manuscript and it helped me to come to terms with everything that happened.”

The film gives a vivid picture of what it means to be a youth going into war.

“In 1940, the threat of mortal combat was very real indeed. It was like coming into a room four times a day where there is someone who doesn’t just want to beat you up – they want to kill you.

“Revisionists might say the Germans lost the Battle of Britain, not that we won it or the Germans never intended to invade, but they had waltzed through Europe bombing everything in sight and for first time realised they could be beaten.”

The film takes up Geoffrey’s story when he was posted to No 92 Squadron at Northolt, arriving in May 1940. The day after, 92 Squadron went into action for the first time since World War One, moving to Hornchurch and flying patrols over Dunkirk. He was later stationed at Duxford and Biggin Hill, with a brief respite period in Pembrey, South Wales.

He was awarded the Distinguished Flying Cross in 1941. In March 1942, he went to 65 Squadron at Debden as a flight Commander and from there to Malta. He led a group of eight Spitfires off HMS Furious to Luqa during Operation Pedestal. Geoffrey suffered severe combat fatigue that same year and finished the war as a gunnery instructor, leaving the RAF in 1961.

“I didn’t know or want any other way of life and I never settled down after the war. We felt like we’d won in 1941 and I’d given up worrying about being killed. Thinking back, I would not have survived. I felt invincible and that’s when you’re done for in combat.”

First Light is on Tuesday, September 14, 9pm on BBC Two as part of the BBC’s Battle of Britain season. www.bbc.co.uk/history