Rhall, who will be based in London, joined Millward Brown in 2006 as AMAP CEO, prior to which he held leadership roles with The Nielsen Company in both the US and Asia Pacific. Earlier in his career, he held senior roles with Roy Morgan Research and the Australian Bureau of Statistics.

Kantar Group CEO Eric Salama said: “I am delighted for Travyn. He has done a superb job in Asia and Africa in growing the offer and building a strong team. He has first-hand experience of the needs of clients as they expand into emerging markets and has experience with global clients and in developed markets such as the US as well.”

Salama also praised Campbell’s contribution to the company, calling her “an outstanding leader”.

“Her tenure included unprecedented market volatility and a rapidly changing media and technology landscape. Under Eileen’s leadership, Millward Brown faced these challenges head on and flourished,” he said.

Campbell’s next role is not yet known but it’s understood to be outside the research sector. She has been with Millward Brown for the past 13 years and was president of global development when she took over from Bob Meyers as CEO in 2007.