He has now opened Clarence Mitchell Communications, with the public affairs agency JBP thought to be among his founding clients.He told The Guardian he intended to continue representing the McCanns "as and when needed" and that he would take individuals, families and companies on as clients.
Mitchell began representing the McCann family full-time in 2007 after he stepped down from his role as director of media monitoring for the Cabinet Office.
He was also the Foreign Office media liaison officer for the McCann parents in the months immediately following their daughter’s disappearance.
Before his government role, Mitchell was a journalist for 25 years, both in print and as a BBC broadcaster. In addition to Burson-Marsteller he has worked for Lewis PR and Freud Communications.
Amanda Pierce, CEO of Burson-Marsteller, said: "I would like to thank him for everything he did here and I wish him the best with his endeavours."