Tom Gleason, president of HRG’s North American operation, is to retire next year.
He became part of the TMC when it bought the US agency Seagate Travel in 2005.
Since then Gleason has played a major role in merging HRG’s operations in the US and Canada.
He will stand down at the end of March 2012.
Kevin Ruffles, HRG’s chief operating officer, said: “Tom has worked tirelessly on behalf of HRG in the short time he has been with us.
“We will miss him and wish him well for a happy and successful retirement with his wife and family.”
The company said Ruffles and Jim Pagano, chief operating officer HRG North America, will continue to oversee the North American business in during Gleason’s transition to retirement.