The account covers brands including Twiglets, Jacob's Cream Crackers and Thai Bites.
Carat said it did not pitch for the account, which it won in April 2004 when Jacob's was owned by Danone.
United Biscuits then bought Jacob's in September 2004 and began a review of its media arrangements, leading to the transfer of the business.
It also changed the creative agency on Jacob's last month, hiring its retained agency Publicis at the expense of Euro RSCG London.
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