The appointment of Tonic, founded last December by former Vizeum directors Geoff Seeley and Tim Elton, follows Yeo Valley’s selection of Banks Hoggins O'Shea FCB to handle creative work.
Tonic will advise on a media strategy for Yeo Valley, starting with a test campaign this summer in the South East.
Creative work is built around the strapline "In a world gone mad, it's sanely delicious" to support specific Yeo Valley yoghurt and ice cream products, as well as the corporate brand.
Ben Cull, marketing director at Yeo Valley Organic, said: "We want to test a number of creative executions, as well as assess the effectiveness of different media. Tonic is now advising us on planning and strategy and will also be helping to ensure that our media buying is as effective as possible."
Its spend is expected to triple to around £3m to support its brands. Yeo Valley Organic uses Bristol-based Taylor & Taylor for its media buying.
Yeo Valley Organic used Delaney Lund Knox Warren and MediaVest for its first ad campaign in 2000.
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