Bert Greeves built his initial Invacar for one of his employees Mr Derry Preston -Cobb. Greeves motorcycles used various power units, mainly Villiers but also British Anzani, an up and coming rider named Reg Everett badgered Bert to produce a racing machine rather than the scramblers which the company was famous for and that machine spawned the 250cc Silverstone and 350cc Oulton and I believe the Silverstone won the 250cc British Championships in 1964.