In 1990, he moved to Stockport County, who paid United between £40,000 and £75,000 for his services. He remained at the club for ten years, during which the club would win promotion on two occasions, and make four Wembley appearances. On 10 March 1993, Gannon verbally abused Stoke City player Mark Stein, who reacted by assaulting Gannon. Gannon made a formal complaint to the police and as a result Stein was later required to appear in court for the attack. The two players' confrontation continued the following month after Gannon's then-girlfriend spat at Stein in a post-match interview. Stein was given a conditional discharge after the court accepted he was under "extreme provocation" from what he claimed was racial abuse. During his early days at the club Gannon was criticised by supporters for his performances, but he soon won them over after moving from centre-half to become a goalscoring midfielder. Stockport fans named him 'The Ghost', due to his knack of 'ghosting' in at the back of the box to score from crosses. He was also nicknamed 'Big Jimbo'.