Eccleshare will join the company as the chairman and chief executive of the Y&R/Wunderman alliance in EMEA. He will also take up the position of head of Y&R Advertising in Europe, succeeding Etienne Boisrond, who will retire at the end of the year.
The move brings Europe in line with other international Y&R markets; the Y&R/ Wunderman alliance has already been extended across the Asia-Pacific region and parts of Latin America.
Eccleshare, who will start in his new position in September, will join Y&R from McKinsey & Company, where he has been responsible for building and leading its European branding practice.
He will report to the Y&R chairman, Mike Dolan. On Wunderman matters he will also report to Daniel Morel, Wunderman's worldwide chairman and chief executive.
Eccleshare said: "Each of these brands is a leader in its sector, and by building closer links between them we can develop a formidable force in marketing communications. The dual challenge of giving leadership to the European networks, while also developing a single proposition, is irresistible."
Dolan said: "In making this change across Europe we sought a distinctive leader. William understands total branding. He's a committed brand builder - a strong strategic thinker with an exceptional ability to execute against client needs."
Before working at McKinsey, Eccleshare was the chairman and chief executive of Ammirati Puris Lintas between January 1996 and January 2000. Before that he worked at J. Walter Thompson. His 18-year tenure there culminated in his post as the network's worldwide director of strategic planning.
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