Mahon was born in Bakersfield, California, and learned to fly while in high school. In 1941 he joined the Royal Air Force, and by the winter was flying combat with No 121 (Eagle) Squadron, composed of American volunteers. Pilot Officer Mahon damaged three German fighters, two FW-190s in April and an Me-109 in May, before scoring his first confirmed victories of two FW-190s, downed in the Saint-Omer area, on June 8, 1942. On July 31 he destroyed two more FW-190s over the Berck-Sur-Mer area and became an Ace while covering the commando raid on Dieppe, August 19, 1942, his 98th fighter pilot mission. At 08:30, flying his Spitfire Vb, nicknamed "Barry", Mahon shot down an FW-190 and another FW-190 before his plane was hit and he was forced to bail out of the burning ship. Landing in the sea, he was taken prisoner. Although Mahon filed a claim for shooting down two Germans that day, he was only given credit for one after the war. Thus, for a tally-record of five confirmed, two probables, three damaged, in 98 combat missions and other brave and heroic deeds, Mahon received the British Distinguished Flying Cross in 1945.

Officially listed as "missing", the British Air Ministry awarded him the Distinguished Flying Cross, noting in his citation that he was "an extremely skillful and confident pilot, whose courage, especially when attacking superior numbers of hostile aircraft, had been unsurpassed."

As a German prisoner, Barry was sent to Stalag Luft III, a special prison camp the Germans reserved for airmen. Barry's first escape was nearly successful, he reached the Czech border before he was recaptured, due to feet so sore he couldnt go on and was placed in solitary confinement. When returned to the prison camp population, he escaped again, this time in 1943.

Recaptured, he was back in the "cooler" when 76 of his comrades slipped out through tunnels in what would later be called "The Great Escape". But for his confinement at the time of the escape, Barry would have been among them.

It was a stroke of fortune for the man who would later serve as a technical advisor during creation of a 1963 movie in which Steve McQueen would portray Barry's character.

Finally liberated by Patton's 3rd Army 29th April 1945. After the war he became the personal pilot for, and later the manager of, Errol Flynn. Having produced a number of Flynn and Gina Lollobrigida pictures, as well as a considerable output of children's programs, Mahon established The Production Machine, a high-tech film production company in Hollywood, making motion pictures for theatrical and television release. Mahon was the first movie producer to adapt and apply computer technology (as well spreadsheet applications, such as MultiPlan) to the breakdown, scheduling, budgeting and financial analysis of feature-length motion pictures and movies-of-the-week for Columbia Pictures.

Mahon was married to Clelle until his death. He is the father of Columbia/CBS producer Doris Keating.

Awards: DFC