Whittaker, who joined Edelman three years ago, said he has quit the role to devote more time to a business portfolio including chairmanships of companies including Retail Decision, Madisons Coffee and Eagle Eye Telematics.
Edelman UK chief executive James Thellusson said he is not looking for another chairman but is, instead, seeking to create an advisory board 'of three to four non-executive consultants, senior players in the industry who can offer their advice on specific areas of the business'.
Thellusson said he is specifically looking for experts in marketing, healthcare and the corporate arena to assist the agency on a retained basis.
Whittaker's decision to quit comes just two months after a reshuffle of the top management at the agency's UK base. This included the appointment of Thellusson as the agency's third CEO in just nine months. He replaced John Mahony who left to set up his own agency after less than a year in the post.
Prior to joining Edelman, Whittaker spent three years as Burson-Marsteller chairman and 13 years as a board director of retail giant Kingfisher.
At Edelman his role included offering reputation advice and 'helping CEOs in trouble'.
Whittaker said he had no immediate plans to carry on this work. He also ruled himself out of becoming a member of Edelman's advisory board.
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