[6] After first team goalkeeper Dave Latchford broke his finger in a match against Bristol City, Cooper made his Birmingham debut on 8 January 1972 against Portsmouth.
[8] Latchford was subsequently recalled during the Easter period,[4] but was dropped after losing form and Cooper brought back into the team for a crunch promotion match against Millwall on 8 April.
[9] Cooper kept his place in the team for the club's FA Cup semi-final defeat the following weekend against Leeds United,[10] and played every match until the end of the season as Birmingham finished second, earning promotion to Division One.
[13] First team goalkeeper Laurie Sivell returned for Ipswich's final league match of the season, but Cooper was signed on a permanent contract in June 1974 for a fee of £23,000.
Cooper missed the league match a week before the final with a back injury and was replaced by Paul Overton, who, in his only appearance for Ipswich, conceded six goals as Town lost 6–1 to Aston Villa.
[18] Cooper returned for the final and kept a clean sheet as Ipswich won 1–0, the club's first major honour since winning the First Division in 1961–62.
[22] At the time goalkeepers could not move their feet before the ball was struck, but he attempted to distract penalty takers by waving his arms and leaning to one side, a technique David James later copied.
During this time, Cooper was the only regular first team member at Ipswich not to play for his country,[22] although he was considered unlucky not to do so, facing competition from Peter Shilton and Ray Clemence.
[2] In 1981, he was also one of several Ipswich players to appear in the film Escape to Victory, with Cooper used as a stand-in for Sylvester Stallone, whose character played in goal.
[33] Although Martin Hodge was bought to replace him, injury meant that Cooper remained first choice goalkeeper for the first half of the 1988–89 season, playing until mid-January.
However, when Hodge recovered, Cooper was allowed to leave; he did not play for Leicester again after a 2–1 win at home to Portsmouth on 14 January,[5] and subsequently signed for Second Division rivals Manchester City for £20,000 on the March 1989 transfer deadline day to serve as backup to Andy Dibble.
[39] Cooper came into the team, but only kept his place for nine matches,[40] his final appearance for Manchester City and in the top division being a 4–0 defeat at Arsenal on 14 October 1989,[35] although he remained at the club until the following summer,[3] when they signed another goalkeeper, Tony Coton.
[44] He did some scouting in north-west England for Ipswich manager and former teammate George Burley, before moving to Tenerife where he runs a golf business.