The agency is currently in negotiations with Bolton to find him a new position within the global network.
The replacement for Bolton in the UK is likely to be an internal appointment, but final decisions are still being made.
The move comes at the end of a difficult year for JWT's London office. It has been hit by a series of international losses amounting to almost £60m in billings.
Last month, the agency was stunned by the loss of its £25.2m Persil account. The account moved to Bartle Bogle Hegarty, ending a 60-year relationship between JWT and the brand. It also weakened JWT's grip on the Unilever business.
The agency has lost the Unilever Bestfoods Lipton Ice Tea account in Europe and is facing a pan-European review of its Knorr cooking sauce account.
Other global realignments affecting the London office this year include the £22m Axa account into Grey's Australian agency and Samsung's global realignment into the Leo Burnett network.
Although JWT pitched for British Airways and Sainsbury's, it has been unsuccessful in securing any significant UK new-business wins.
Bolton was part of the WPP team that won the HSBC and Samsung businesses last year. He has been JWT's chief executive since 2001. Before that, he spent a two-year stint as the president of FCB San Francisco. He also worked for FCB in Malaysia as the managing director of its Malaysia and South-East Asia office.
Bolton started his career at Ogilvy & Mather in the late 80s and became the creative services director in its Thailand office a few years later.
In 1992, he moved back to London as the worldwide management supervisor on American Express.
JWT would not comment as Campaign went to press.
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