John Davis started as an apprentice with British Leyland at Longbridge, Birmingham, in 1972. Born and brought up in Birmingham - the industrial center of Britain - Davis worked for the company in a turbulent period during which it was nationalized. Despite this Davis was able to study for a degree in mechanical engineering, paid for by the company. When he graduated with a BSc in 1979 he went on to do postgraduate studies at Imperial College, University of London, working specifically on aerodynamics. He was still working for British Leyland when he gained his doctorate.During that period, however, the Imperial College windtunnel was used by several Formula 1 teams, notably Williams and Lotus. Davis was drawn into the work and in 1982 was hired by Team Lotus to be its aerodynamicist and head of research and development, which meant working with technical director Gerard Ducarouge and Ayrton Senna. He then moved across to Lotus Engineering, where he worked under Peter Wright, developing active suspension technology and in 1987 Senna won the Monaco and Detroit GPs using an active car. Lotus Engineering was too busy to continue the active program for the racing team in 1988 and so Davis worked on road car development until the end of 1990 when Wright took him back to Team Lotus, having taken over the racing team in partnership with Peter Collins. Davis became head of research and development but in the middle of 1992 Ducarouge asked him to join Ligier and he moved to Magny-Cours to be the French team's director of research and development.Davis stayed with Ligier during the turbulent period until the end of 1994 when Ducarouge departed. Davis went to work for electronics company Pi Research in Cambridge, England, but in 1996 found himself in America, as a consultant engineer for Patrick Racing. Before the end of the year, however, he had been recruited by Jordan Grand Prix to head the team's windtunnel program and he soon became chief race and development engineer as well.In November 1999 he joined Arrows as head of research and development. Frustrated in that role he moved to Minardi at the end of 2001 and then a year later joined the aerodynamic team at Williams.