Haslam debuted at the 1978 TT races with a best place of fourth in the Formula Two race, later making his mark in 1981, when he was named winner of the Formula 1 race, only for the organisers to give the win the following day to Graeme Crosby.
In the 1978 TT races, Haslam secured a fourth place finish in the Formula Two category. In 1981, he was named the Formula 1 race winner but had his victory contested and ultimately awarded to Graeme Crosby by the event organizers.