I've used Malcolm for servicing my large format lenses, and I've bought a couple of lenses from him - a 135mm Elmar and my latest, which I should receive on Tuesday, a 35mm Summaron screw with an M adaptor.
When I was living in the area, I'd go over to see him and spent an enjoyable couple of hours learning each time. He has some genuine Bugatti vises, obtained from the factory at Mulhouse by the late Hugh Conway. They are beautiful objects in their own right.
A few years ago, he admitted that he can't repair the electronics in the newer cameras, but anything mechanical or optical he can fix. He's also got a lens coating machine, although one of former clients, James Ravilious, used to get him to take the coatings off the lenses.
Nick