Kelly Clark, the chief executive of MindShare UK, said he had decided to resign the account because it contradicted his agency's philosophy of "joined-up media".
"We've had a long and rewarding relationship with the Telegraph but we don't think we can accomplish what they want unless the planning and buying disciplines are together," he said. "We don't think this is an accountable way and we think it's sensible for them to find other partners."
CHI has handled the Telegraph Group's creative account since 2001. Mark Dixon, the Telegraph Group's marketing director, said: "After six years with MindShare, we feel that it's time for a new approach. The opportunity that presents itself at Naked Inside, with media planning and creative working side by side, is too good to miss."
It raises questions, however, as to what agency would want to handle a media buying-only newspaper account. Typically, these are price- or promotion-driven and have to be turned around at short notice.
The Telegraph Group becomes the second CHI client to use Naked Inside, led by Initiative Media's former planning director, Tim Allnutt. Earlier this month, Carphone Warehouse instructed the outfit to create a strategy to drive footfall to its stores over Christmas.
Hollinger International, the owner of the Telegraph Group, faces dismemberment following the departure of Conrad Black this week.
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