In December 2010, he was made joint caretaker manager at Vale, along with Mark Grew, following the departure of Adams. Vale were beaten 5–0 by Rotherham United in his first game in charge, but rallied to beat Burton Albion 2–1, before Jim Gannon was appointed manager. Gannon retained Horsfield as his assistant. On the way to a match at Aldershot on 25 February, Gannon left the team bus after an apparent bust-up with Horsfield. The national media reported that Gannon granted Horsfield's request for a day off for family reasons but then wrote to the board complaining about his conduct. Having been shown the letter by a director, Horsfield confronted Gannon over the issue. After an internal inquiry, during which Horsfield stayed away from the club, no disciplinary action was taken against either party. Gannon was sacked on 21 March, and Grew was appointed as caretaker-manager with Horsfield as his assistant.