Born in Newport in south Wales, Rees started racing in 1959 with a Lotus 11 but he quickly moved into Formula Junior and became a star, spending two years in a team which was being run by Jackie Oliver's father. In 1961 he bought one of the new Lotus 20 Formula Junior cars and won the British Championship and for 1962 and 1963 he was hired to drive for the factory Lotus team. In 1964 he joined Roy Winkelmann Racing as driver/team manager and raced a Brabham in Formula 2 with increasing success, his first victory coming at Reims in July that year - ahead of Jack Brabham, Mike Spence, Jim Clark and Denny Hulme.The following year Rees brought Jochen Rindt under the Winkelmann banner with two new Brabham BT16s and the duo raced Winkelmann Brabhams in F2 with considerable success until the end of the 1968 season: Rees finishing third in the 1966 European F2 Championship. He started in three F1 races in this period but all in F2 machinery. In 1969 Winkelmann switched to Lotus chassis and Rees decided that it was time to retire from driving.In March 1969 he joined Robin Herd, Max Mosley and Graham Coaker to set up March Engineering. His job was to run the March F1 team which he did for a couple of years before joining Shadow as team manager. He remained with the team until the end of 1976 when he joined Jackie Oliver and a group of others in establishing the Arrows F1 team. He was the Arrows team manager until March 1991 when he became financial director. He sold his shares in the company to Tom Walkinshaw in 1996.