The news is a vote of confidence in the agency, but will come as a blow to WPP's Berlin Cameron/Red Cell, which handles the brand in the US.
Berlin Cameron was added to Coke's US creative roster in January last year, replacing McCann-Erickson's New York shop. The agency developed the "real" positioning, and created a campaign using Hollywood stars.
Mother's 60-second commercial, entitled "I wish", also uses the "real" strategy.
It was shot using a cinematic "one-shot" format and stars the singer Sharlene Hector.
Coke operates a complicated roster system and has a tradition of airing ads across different markets. This will see a campaign by McCann-Erickson Madrid screened in the UK shortly.
However, Mother says it is not working on any additional ads for the US and has not been told whether the second ad in the campaign, expected to break in the spring, will also be launched in the US.
Mother was appointed to the flagship Coke UK account in September.
The decision to run the ad in the US follows Charlotte Oades' promotion to president of Coca-Cola Great Britain at the end of last year.
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