You must be knocking on a bit if you are the same one I read about in my distant childhood
Biggles first appears as a teenaged "scout" (fighter) pilot in the Royal Flying Corps (RFC) during World War I. He has joined the RFC in 1916 at the young age of 17, having conveniently "lost" his birth certificate. Biggles represents a particularly "British" hero, combining professionalism with a gentlemanly air. Under the stress of combat he develops from a slightly hysterical youth prone to practical jokes to a calm, confident, competent leader. He is occasionally given "special" (secret) missions by the shadowy figure of Colonel (initially "Major") Raymond (Wing Commander or Air Commodore in later books), who is already involved with the intelligence side of operations. Biggles is accompanied by his cousin Algernon ('Algy') Lacey and his mechanic Flight Sergeant Smyth, who are to accompany Biggles on his adventures after the war; added to the team in 1935 is the teenager Ginger Hebblethwaite.