Williams was born in Nottingham, England. He started his racing on UK race circuits in 1964 and won the 250 cc class of the 1964 Thruxton 500 race on an AJS model 14 CSR partnered by Tony Wood. He first entered the Isle of ManManx Grand Prix in 1964 on a Norton In 1965 he entered the Senior race on his DunstallNorton Dominator 500cc twin suffering con-rod breakage of the left cylinder when lying 3rd but scored a third place in Lightweight 250cc category riding an Orpin Greeves Silverstone. Williams entered selected Grand Prix races from 1966. He also regularly competed in TT races from 1966, scoring one 1st place and seven 2nd places. He won the 1966 North West 200 500cc race in Northern Ireland on a Matchless, and placed 2nd in the 250cc class on a Greeves Silverstone His best Grand Prix season was in 1967 when he finished in fourth place in the 500cc world championship on a Matchless motorcycle. He had a long-standing relationship with sponsor Tom Arter, riding his Arter-AJS and Arter-Matchless machines which were later developed with special lightweight frames, disc brakes and six-spoke, solid-cast Elektron wheels dubbed "cart wheels" and artillery wheels by the UK press. He raced in the era of Giacomo Agostini, Barry Sheene, Mick Grant, Percy Tait, Tony Jefferies, Paul Smart, Dave Potter and John Cooper. In 1969 Williams and Arter started a new project with a prototype Weslake twin cylinder 500cc engine to replace the 1950s Matchless G50 which was abandoned as the engine project failed in 1999 As a Norton employee from 1969, Williams entered larger-capacity races on Norton Commando twins. He teamed with Charley Sanby to win the 1969 Thruxton 500 endurance race and was placed second in the 750 cc class Production TT race in 1970. Williams won his only world championship race in 1971 in the 350cc Ulster Grand Prix, and also won the 1973 Isle of Man F750 TT on a John Player Norton Special with a semi-monocoque frame, in the role of team designer/rider. The machine was designed as an integrated package with a Peel-type fairing incorporating handlebar blisters which helped to reduce the drag coefficient to 0.39. His racing career was cut short by injuries received in an accident at Oulton Park on August Bank Holiday 1974.
Career after racing
In the 1970s, Williams presented the intelligent face of bikers at public appearances giving open lectures at universities. He provided insight into the engineering issues of racing the restricted budget Works Norton against multi-cylinder bikes from Japan, highlighting the pros and cons of using the 1940s designed Norton engine. The crank shaft of the 360 degree parallel twin was supported on only two main bearings and as more power was developed from the engine a noticeable flex could be measured using a dial gauge placed on the end of the shaft. In the later 1970s Williams operated a Kawasaki motorcycle dealership in Southampton. More recently he has been involved in the development of a carbon-fibremonocoque designed superbike at Lotus Cars and an electric powered racing bike, the EV-0 RR, planned for an outing at the TTXGPZero Emissions race at the Isle of Man TT in June 2009. He has a number of patents relating to frame and engine design. For 2013, Williams established a new business Peter Williams Motorcycles to recreate a limited number of his 1973 Norton Monocoque race bikes