A spokesman said that Longworth was emigrating to San Francisco with his family.
Longworth joined Marlow Foods in July 2003 as European marketing director for its meat substitute brand Quorn. In this role he was responsible for reinforcing Quorn’s position as a mainstream, healthy eating brand in the UK and Europe, including advertising, media, new product development, direct marketing and PR.
Prior to Marlow Foods, he was marketing director for the UK and Ireland at Kellogg.
Longworth said: “I have enjoyed a fantastic few years working with a great team at Marlow Foods and Premier Foods. I’m delighted that the efforts of the team have delivered such strong business results and that Premier Foods is committed to continued long-term investment in the brand.”