The US food company appointed Grey London as its lead UK agency in 2015, following a pitch against HeyHuman. The account, believed to be worth £11m, included some activation work for Häagen-Dazs and Old El Paso.
The pitch was led by General Mills’ then-UK marketing director Jennifer Jorgensen, and managed by Oystercatchers.
Grey London was unavailable for comment. A General Mills spokesperson said: "We regularly review our agency roster to fit the requirements of our business, but do not comment on individual tenders."
General Mills works with a raft of agencies, including Saatchi & Saatchi, which handles Häagen-Dazs, and 72andsunny, which it appointed to handle US creative duties in 2016. Global media planning and buying is managed by GroupM’s Mindshare.
Last year, Nature Valley recruited British tennis star Johanna Konta as a brand ambassador, and pitted the British number one against former Wimbledon champion Pat Cash in a match at Westfield London.
In June, former Coca-Cola vice-president, strategic marketing Ivan Pollard joined General Mills as global chief marketing officer as part of a major restructure which saw the company cut hundreds of roles worldwide.