Thompson started racing in the BTCC in a privately entered Peugeot 405 in 1994, his performances earning him a factory Vauxhall drive for 1995. He became the youngest ever race-winner that year, also taking two pole positions, before his season was cut short by a crash at Knockhill giving him an eye injury. 1996 was a transitional year with the new Vauxhall Vectra, although Thompson took a victory at Snetterton, moving up from fifth in a two-lap burst in which Roberto Ravaglia and Rickard Rydell collided, Joachim Winkelhock spun, and Alain Menu broke down.