Justin started his rallying career in 1992 when he contested the Peugeot Rally Challenge in a 205 1.9 GTi. He was runner-up in both the 1993 and 1994 series, before switching to a new car for the 1995 season.

In 1996, Justin - together with new co-driver Andrew Bargery - secured the title of British Junior Rally Champion. He won four of the six rounds and the Peugeot Challenge along the way. Justin also finished third overall in the 1996 British Rally Championship - the first Amateur Driver - and collected the Gunk Reliability award for his 100% finishing record. Justin completed the year with his first works drive, joining Peugeot for the RAC Rally.

In 1997, he contested all rounds of the British Rally Championship and a consistent year saw him end the season as the first non-kit car in the series.

For the 1998 British Championship Justin took to a new car to contest the new "Super 1600" category. The team had a year of mixed fortunes as the car was continually developed to suit the British forests. Justin demonstrated the car’s potential with a category win and a career-best of eighth overall on the Ulster International rally.

In 1999, Justin continued to drive for Peugeot. He won five out of the six rounds in the championship, easily winning the Ferodo Super 1600 category in the British Championship. He finished the year with a career-best sixth overall on the Manx International Rally.

After winning the championship, Justin and co-driver Andrew Bargery retained their drive for 2000. Two non-finishes prevented Justin from retaining the title, but some stunning drives - including third overall on the Manx – established him as the quickest 1600 driver.

2001 saw the British Rally Championship cancelled due to Foot & Mouth disease but in 2002, Justin again took the Super 1600 honours and finished the season as runner-up outright in the British Rally Championship. The highlight of his year was being asked by Marlboro Mitsubishi Ralliart to stand in for injured works driver Alister McRae in the manufacturer’s third official entry, on his home event, the Rally of Great Britain.