Dixon, who is leaving for personal reasons, had worked at LBM for nine years and is not being directly replaced. Instead, chief operating officer Mark Bates has been promoted to the new role of managing director.
John Lord, market leader of UK and Ireland sales at D&B, has joined LBM as the company's first group sales and marketing director; while Gary Powell joins as sales director for LBM's London operations, from his role as sales director at Equifax.
Four new members of staff are also set to take senior roles in the company's marketing department.
Keith Pacey, LBM chairman, said: "Ben has given nine years of loyal service to LBM and I would like to thank him for the major contribution that he made to the business over that period."