The divorce means that the £8 million worth of Robinsons business currently held by the agency will be put out to pitch.
Agency Insight will handle the pitch process for Robinsons, with a view to having a new agency in place by July.
This week's announcement of the split culminates the mounting discomfort within Britvic, the UK distributor of Pepsi, at the burgeoning relationship between Coke and the WPP-owned Red Cell.
Matters came to a head in February when Coca-Cola switched the US account for Coke Classic out of McCann-Erickson and into Berlin Cameron - part of the Red Cell stable.
Lee Daley, Red Cell's global chief, and Andrew Marsden, the Britvic category director, discussed the situation after HHCL joined the Red Cell network earlier this year, but failed to resolve the clash of accounts.
Marsden said: "The time is right to look for a fresh approach."
Daley described the parting, which will take place after the three commercials currently in production have aired, as "a sad day for the agency". But he added: "Inevitably these things do happen when local agencies join networks."
The news increases the likelihood that television work produced by New York's Berlin Cameron will now run in Britain.
Red Cell sources deny the split was precipitated by a promise of work from Coke. However, HHCL could be asked to co-ordinate US-sourced work in the UK. Network chiefs are also hopeful that the agency's extensive soft drinks experience will lead to it originating creative work for Coke brands.
Berlin Cameron is said to have produced up to half-a- dozen commercials suitable for screening in Britain. McCann and Mother both presented work for the Classic brand, but it is unclear at present if either work will run in the future.