The United Biscuits brief sees icas taking over publicity for a range of iconic brands, including McVities, KP Nuts and Jaffa Cakes.
The agency will seek to flag up the company's efforts to make its products more healthy. Earlier this year, McVities removed man-made trans-fats, linked to increased risk of heart disease, from the recipes of most of its products.
The appointment comes as icas reveals that it has been the subject of a partial management buyout.
Joint owner Anne Layton has sold all her shares in the agency and will now ‘pursue other avenues', according to a statement.
Board directors Emma Wright and Zoe Ward-Waring have invested their own money in the 40-strong agency, the former becoming MD, the latter deputy MD.
Carl Courtney moves from MD to an executive chairman role, and plans to ‘get back involved with more client work' for the Covent Garden and Hemel Hempstead-based agency.
Wright is heading the United Biscuits account, reporting to UK trade PR and comms manager Jessica Wylie. Cirkle will continue to work alongside icas until Christmas. Icas will take over in the new year.
‘Losing the account is a blow but it has been our best year with the client,' said Cirkle director Caroline Kinsey. She spoke on the eve of winning a Grocery Advertising and Marketing Industry Award for United.