Warburtons already works with a number of regional promotional agencies, including KLP Euro RSCG, Chemistry Digital Nottingham and Brahm in Leeds. It used to work with the now-defunct WWAV Rapp Collins Leeds, which closed in June.
The review follows the appointment of Richard Hayes, who joined as the marketing director in May from the distiller Whyte & Mackay, where he held an equivalent title.
Bartle Bogle Hegarty has handled Warburtons' advertising since 1998. In January, the agency developed the brand's first national advertising strategy, eschewing its traditional, regional approach.
BBH is unaffected by the review.