In Ganley raced for the Marlboro BRM team and finished 13th in the Championship with 4 points. His highest finish for the season was 4th at the Nürburgring. For the season Ganley signed up to drive an Iso–Marlboro car for Frank Williams Racing. At the 1973 Canadian Grand Prix he was almost declared the winner because of a timing mix up with the pace car; when the results were corrected, Ganley was classified sixth.