He moved from CEO to chairman in 2009 and to non-executive director in 2011. As part of a planned withdrawal, he has now left the board altogether.
However, he still owns nearly 10% of the business and will continue in a part-time role as director of business development for the DriverTrett dispute resolution business as an employee of Driver Consult Ltd.
Dave Webster, who succeeded him as CEO, said: "I would like to personally thank Stephen for providing the opportunity to join the company in 1999 and supporting my development through to the position I have today. Now is the right time for this final transition and Stephen leaves the board with the company performing at the top end of management's expectations and nicely positioned for the remainder of this current financial year and beyond."