Paul Nelson has left John Martin Group (JMG) after 17 years as finance director because, it is believed, the founder and chairman blocked his proposed management buy-out.

The £252m turnover, 34 dealership business is expected to retreat to dealerships in Edinburgh and Aberdeen. Other sites are likely to be sold.

Both sides insist the parting was amicable. Nelson says: “I’m disappointed to go after such a long time with the organization but I’m not sure I could fully support John Martin’s future vision for the company.”

Nelson now plans to set up a dealer development business working in Scotland for car manufacturers.

Brian Stock, who left JMG in 1998 becomes finance director. He retains the personnel role he took on his return.

John Martin, 69, wanted his son John to take control of the business when he retired, but he died suddenly after playing in a football match last autumn. A second son, David, has no interest in the motor trade.

Gordon Nisbet, JMG managing director, says: “John Martin remains completely committed to his business and has no intention of selling out. We are having a complete review and will concentrate on a smaller number of franchises.”

JMG holds franchises for 13 manufacturers.