After starting his career on motorcycles in Junior Grass track and Speedway, he first raced in cars in 1980 in Formula Ford.

Middlehurst took Class C titles in the BARC Production Saloon Car Championship in both 1988 and 1989 driving a Volkswagen Golf GTI.

[2] Middlehurst claimed the overall title in 1990 at the wheel of a Ford Sierra RS Cosworth[2] which led to a drive in the British Touring Car Championship.

His first full BTCC season came in 1991 for Graham Goode Racing in a Ford Sierra RS Cosworth.

[5] He has won the Glover Trophy at the Goodwood Revival a total of nine times between 2011 and 2024 in Jim Clark's 1963 championship-winning Lotus 25.