Heyer, who joined Coca-Cola in 2001, had been one of the instigators of the move from Interpublic to WPP, because he has a relationship with the chief executive Sir Martin Sorrell.
However, with Heyer's resignation yesterday from the number two role at Coke following the appointment of Neville Isdell as chief executive and chairman, there are reports that Interpublic could see a return of some of the work it has lost.
The most notable loss for Interpublic was at the beginning of 2003, when McCann Erickson saw the flagship Coke Classic account shift into WPP's Berlin Cameron/Red Cell New York.
There have been several other losses to non-WPP agencies including the Coke Classic brand in the UK, which is now handled by independent creative agency Mother; the French creative account, which moved from McCann Erickson to BETC Euro RSCG; and losses in Singapore and Vietnam.
Interpublic's Universal McCann also lost the $350m Coke US media buying account after 20 years last year, with Coke shifting the work into Publicis Groupe-owned agency Starcom MediaVest.
According to a report in the Wall Street Journal, McCanns' chief executive John Dooner still has a number of close contacts at Coca-Cola and, with the departure of Heyer, the newspaper says that he has been in contact with Isdell, and that McCanns and Coke have been in conversations.
Coke has been struggling in recent years to pin down exactly what it wants to do with its advertising. While Pepsi has turned to celebrities with wide youth appeal, such as Beyonce and Britney Spears, Coke has retained its feel-good, warm and fuzzy advertising.
Only this month an ad for the soft drink that showed a man rubbing a can of Coke under his armpit then giving it to his unsuspecting friend was pulled from US television, not because of a widespread consumer backlash but, according to reports, because one of Coke's directors, Donald Keough, did not like the spot. It had tested very well with the youth market and was scheduled to be screened during college basketball matches, but was spotted by Keough when it aired during a golf tournament.
If you have an opinion on this or any other issue raised on Brand Republic, join the debate in the .