Jenkins spent his childhood at Neston, a little town on the Wirral Peninsular, close to the English-Welsh border, and within easy reach of Liverpool. He studied at Wirral Grammar School and later at the Liverpool College of Art and was a regular spectator at both Aintree and Oulton Park. He graduated with a Bachelor's degree in Industrial Design and drifted through a series of jobs until he found his way into F1 racing in 1978, joining the small team at Leamington Spa, preparing old Lotuses for Hector Rebaque - one of the last of the F1 privateer efforts.In 1979 he was hired by Ron Dennis's Project 4 Formula 2 operation. A year later Project 4 took over McLaren and Jenkins found himself as right-hand man to design boss John Barnard. He engineered John Watson for several years, winning a handful of races - notably Watson's remarkable 1983 victory at Long Beach where he won from 22nd on the grid. The following year he engineered Alain Prost but they lost the World title by half a point to McLaren team mate Niki Lauda and his engineer Tim Wright. At the end of the year Jenkins was offered a job by Roger Penske to work in Indycar racing and he jumped at the chance - wishing to get out from under the shadow of Barnard. At Indianapolis in 1985 Jenkins won the 500 at his first attempt - engineering Danny Sullivan's Penske March. He spent the rest of the year flying backwards and forwards across the Atlantic between the races and Penske's British base at Poole in Dorset.The Jenkins-designed Penske PC15 and PC16 were sophisticated but not very successful and Jenkins was dumped by Penske in mid-1987. He joined the fledgling Moneytron Onyx F1 team which entered F1 in 1989 with Stefan Johansson and Bertrand Gachot as drivers. In July Johansson gave the team its first point at Paul Ricard and in Portugal the Swede finished third. Unfortunately at the end of the year the management fell out with Moneytron boss Jean-Pierre Van Rossem and the bizarre Belgian sold the outfit to eccentric Swiss millionaire Peter Monteverdi. Jenkins quit and took the post of Technical Director at Footwork - to design the Porsche-engined FA12. The engine was not a success but Jenkins stayed with the team until February 1996 when he moved to become technical director the new Stewart Grand Prix team. He remained in that role until the end of 1998 when his contract was not renewed. He spent several months looking at various jobs on offer, having lengthy talks with Benetton, Sauber and the Ford Motor Company (which was planning a sportscar program) but decided in June 1999 that he would join Prost, overseeing the design of the Prost-Peugeot AP03 for the 2000 season. Jenkins was fired by Prost in the middle of 2000 and then disappeared from the F1 scene.