Australian racer Brian McGuire was a successful Formula 3 racer in 1971 and 1972 in Australian International Racing Organisation Brabhams alongside Alan Jones and Allan McCully. In 1976 he bought a 1975 Williams and raced it in the British Shellsport category (a mixture of F1 and F5000 machinery) winning in the wet at Thruxton. The car proved to be less than competitive, however, and McGuire finished only eighth in the championship. The car was reworked in the winter of 1976-77 and reappeared as the McGuire BM1. It was entered for the British GP but failed to qualify and McGuire then concentrated on British national races. He was killed at the wheel of the car at Brands Hatch later that year.