Westbury's career falls neatly into two halves, the first as a first class hillclimber, the second as a circuit racer. He started hillclimbing in 1962 with a Cooper-Daimler, and when the V8 was dropped into his own Felday chassis in 1965 his first British hill-climb championship was duly attained. For the following year Westbury got his hands on the Ferguson P99 4WD, which proved almost unbeatable. Although he continued to compete in 1965, Peter was busy building up his Felday Engineering firm, but he made a successful transition to Formula 3 in 1967 with a Brabham BT21. He won races at Silverstone, Chimay and Clermont Ferrand, and took further victories at Chimay again and Reims in 1968. In '67 he also had an outing in the 500 mile race at Brands Hatch in Mike de Udy's Lola T70 Mk.3 Chevy. During the year, Westbury resurrected BRM's 4WD project for use in the RAC Hill Climb Championship. It is quite a coincidence that Westbury drove the Ferguson P99 to an easy British hill climb title win in 1964, the year in which the P67 was first developed and that in 1968 he saw the hill-climbing potential of the P67 just before the F1 community jumped on the bandwagon in 1969. '68 also saw a couple of Formula 2 drives, before a full season in 1969 with his own Brabham BT50 which yielded second place in the Lottery GP at Monza and fifth in the F2 class of the German GP. Peter was given a chance to try a pukka F1 machine when he joined BRM for the 1970 US GP, but the car suffered a blown engine and the disappointed driver failed to qualify. He was a consistent top-six finisher in Formula 2 during 1970-71 but results sagged the following year. In '71 driving for Scuderia Filipinetti he partnered Jo Bonnier in a Lola T212 Ford at the BOAC 1000km race at Brand Hatch and Mike Parkes in the Targa Florio taking 5th and 2nd in class. In '72 he drove at Le Mans in the Maranello Concessionnaires Ferrari 365 GTB/4. Driving with John Hine they retired with engine problems. Westbury retired from racing in 1973.