He was unable to earn a winners' medal with United, despite playing for the club during a successful period. He was ruled out of the 1963 FA Cup Final victory due to a shoulder injury, and a succession of injuries meant that he could not play enough games to qualify for a league championship medal in the 1964–65 season, and he was sold during the first half of their title-winning campaign in 1966–67. They finished runners-up to Wolverhampton Wanderers in 1959. During his United career, Gregg kept 48 clean sheets in 247 appearances.