as pointed out, he did win 2. Mark had a different class to the other riders, Louis, Nicholls, Screen, Smith etc never won a GP despite being in GP's. i seem to remember Martin Dugard won a GP, does that make him better than Nicholls/Louis.
Personally for me Loram is head & shoulders above other Brits of the time... at the end of the day he became World Champion through some outstanding rides that season