The firm was appointed after a competitive pitch believed to have climaxed with a head-to-head against Nelson Bostock.
The decision consolidates Red's relationship with Dairy Crest as it already handles PR for Clover.
The account will be handled by Red board director Mirella Cameran, working with corporate comms manager Sinead Noble and reporting to the individual marketing directors on Dairy Crest's business units.
Cameran said: 'There is an emphasis on brands where it is felt there is scope for improvement in terms of sales. Clover is important, as is Cathedral City and Del Monte.'
The agency is also tasked with promoting home deliveries of milk. Two years ago Dairy Crest acquired Unigate's dairy and cheese business, making it the UK's biggest purchaser of milk, buying three billion litres annually.
Red takes over from Osborne PR, which has worked with the company since 1983 but did not repitch.
Other products to be promoted by Red include the milkshake range Frijj and Wexford cheeses.
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