In addition, Mark Penn – currently managing partner of The Stagwell Group, which bought Harris at the beginning of the year – will be chairman.

Prior to this appointment, Gerzema (pictured) and Johnson were senior executives at Young & Rubicam Group. Gerzema was chairman/CEO and Johnson was president at BAV Consulting which oversees the analytic brand and consumer behaviour survey, BrandAsset Valuator.

Jonathan Gardner will be chief operating officer. He joins from public affairs firm, Subject Matter, where he was also COO and he has also worked at Penn Shoen Berland.

Gerzema said: "Harris is a trusted source of insights and social intelligence for leaders navigating a marketplace, culture and society in a time of radical transformation. We have one of the most admired communities of clients and colleagues who are united in the mission of making sense of a world that is moving faster than ever before."