Allan's professional life was rooted in Honda's UK operations, where he worked as a test driver, and Synchro Motorsport gave him a competitive outlet in keeping with that Honda affiliation. The team operated on a grassroots level while maintaining a professional approach to preparation, and for Allan the racing and testing roles were essentially continuous — the same machines he raced on weekends were variants of what he evaluated during the working week.
Allan began racing competitively in the National Saloon Car Championship with Synchro Motorsport, driving a Honda Civic. He finished fourteenth in the standings with sixteen points in his debut campaign and competed in the series for two further seasons, improving to tenth in 1999 before returning to fourteenth in 2000. During those seasons he also entered one race of the Belgian Procar in each year, giving him occasional exposure to continental saloon car competition alongside his domestic programme.
For 2001 Allan stepped up to the British Touring Car Championship, driving a Honda Accord for Synchro Motorsport in the Production Class. He finished twelfth in the championship that year, missing three rounds; Mark Lemmer substituted in two of the absent rounds. In 2002 he made a late entry to the BTCC, now in a Honda Civic Type-R alongside James Kaye, who would go on to win the Production class title that season. Allan finished ninth in the championship, running consistently if typically behind his more successful team-mate across the season.
In 2007 Allan co-drove an ELR Honda Civic Type-R in the Britcar 24 Hour at Silverstone alongside Mark Hein and Peter Venn, completing 564 laps and finishing twelfth overall and second in class. The result underscored his strengths in long-distance reliability events over his more intermittent outright-pace performances in the short-race BTCC format.
In 2011 Allan returned to competition in the Dunlop Production GTN Championship, driving a Honda Jazz. He scored his final competitive victory at the Brands Hatch night race in November, which proved to be the last championship start of his career. Synchro Motorsport did not enter the series in 2012, concentrating instead on longer-distance events.
At approximately 11:30 on the morning of Tuesday 3 July 2012, Allan was killed at Millbrook Proving Ground in Bedfordshire. The car he was testing lost control and rolled several times; four other occupants of the vehicle suffered injuries described as non-life-threatening. He was 47 years old.
As a mark of respect, Synchro Motorsport painted his name on the side of the Honda Jazz they entered in the Britcar MSA British Endurance Championship 24-hour race at Silverstone on 22–23 September 2012 — an event he had originally been expected to contest. The car was driven by former team-mates Martin Byford, Alyn James, Dan Ludlow, and Stephen Richie in his honour.