Group Captain Lionel Wilmot Brabazon Rees, was a Welsh aviator, flying ace, and a recipient of the Victoria Cross, the highest award for gallantry in the face of the enemy that can be awarded to British and Commonwealth forces. He was credited with eight confirmed aerial victories, comprising one enemy aircraft captured, one destroyed, one "forced to land" and five "driven down". Rees and his gunner, Flight Sergeant James McKinley Hargreaves, were the only two airmen to become aces flying the earliest purpose-built British fighter aeroplane, the Vickers Gunbus.

The Vickers F.B.5 was a British two-seat pusher military biplane of the First World War. Armed with a single .303 in (7.7 mm) Lewis gun operated by the observer in the front of the nacelle, it was the first aircraft purpose-built for air-to-air combat to see service, making it the world's first operational fighter aircraft.