Gilbert-Scott began racing in the Formula Ford British championship in 1981. He progressed steadily through the formula over several seasons before achieving significant results in 1983, when he won both the RAC Formula Ford Championship and the Townsend Thoresen Formula Ford Championship and claimed the Formula Ford Festival title. The Festival was among the most competitive single-seater events in Britain, attracting large international grids, and Gilbert-Scott's 1983 victory established him as a prospect of genuine ability.
In 1986, Gilbert-Scott stepped up to Formula Three with the Chuck McCarthy Racing team, finishing eleventh overall in the championship. The following year he raced in the FIA International Formula 3000 championship and entered sportscar events including the World Sportscar Championship and the All Japan Sports Prototype Championship.
His most significant European result came at the 1989 24 Hours of Le Mans, where he raced as part of the Silk Cut Jaguar team in a Jaguar XJR-9, sharing with Patrick Tambay and Jan Lammers. The entry finished fourth overall. That same year, driving for Eddie Jordan Racing in the British Formula 3000 series, he finished second overall in the championship — one of the strongest performances by a British driver in that formula during the late 1980s.
He competed in International Formula 3000 again in 1990 for Leyton House and in 1991 for Roni Motorsport, gaining further single-seater experience against the grid that supplied Formula One teams with most of their future drivers.
Gilbert-Scott relocated to Japan for the 1992 season, joining the Stellar International team in the Japanese Formula 3000 championship. He remained in the Japanese domestic scene for the remainder of his competitive career, racing in the Japanese Touring Car Championship with the Auto Tech Racing organisation.
In 1993, Gilbert-Scott won the JTCC JTC-2 class driving a BMW M3 for the Auto Tech Racing team, taking five victories including four consecutive wins across the season and accumulating 134 points. The following year he finished second in Japanese Formula 3000 with three victories and 45 points.
He competed in the early seasons of Formula Nippon — the premier Japanese single-seater series — in 1996 and 1997. His final Le Mans appearance came in 1997 with the Gulf Team Davidoff entry, driving a McLaren F1 GTR alongside Ray Bellm and Masanori Sekiya. The car did not finish.
Gilbert-Scott is descended from a notable lineage of British architects. He is a direct descendant of both Sir George Gilbert Scott, the Victorian Gothic revivalist, and Sir Giles Gilbert Scott, who designed Liverpool Cathedral, Battersea Power Station, and the classic British red telephone box. His mother's family is connected to the Morgan Car Company.
Following his retirement from driving, Gilbert-Scott managed Takuma Sato from 2001 until 2009, a period that covered Sato's graduation to Formula One with Jordan and BAR Honda, and subsequent years in grand prix racing. The relationship represented a significant element of Sato's early international career infrastructure.