Thompson’s appointment to Grass Roots' Putney office follows a number of recent business wins for the agency in the financial, automotive and IT sector.
Thompson spent more than 11 years at Ashfield Meetings & Events (formerly Universal World Events) before leaving in July 2012 to join W&O Events.
Hannah Wilkinson, client services director for Grass Roots Meetings & Events, said: "With a variety of market experience, James is an ideal addition to the team. He brings the right style, aptitude and breadth of skills that are needed on key accounts. In the last six months we have defined our strategy, centralised teams in sales and solutions and up-skilled our people to develop solutions for clients based on multiple event disciplines. James fits into this picture perfectly and we are delighted to have him on board."
Thompson added: "There are few businesses that can match Grass Roots for the breadth of their meetings and events services and I'm looking forward to playing my part in keeping the momentum going around key accounts."