In a career disrupted by numerous nose, toe and rib fractures, he made his Football League début on 11 October 1924 for West Ham v. Bury and went on to play for 8 Football League clubs. 71 of Peter Cowper’s 96 Football League appearances were with New Brighton, his most successful campaign being 1928–29 when he was the Rakers’ top goal scorer with 16 goals in 40 games – all of them coming from outside-right. He gained a Cheshire County League medal with Wigan Athletic, turning out in 37 League games and scoring 13 goals including 4 against Macclesfield Town. The following season he won a Cheshire County League runners-up medal with Altrincham. Coming to Haig Avenue just before the transfer deadline, his two appearances were as deputy for Ralph Hills who was suffering from a damaged ankle. He scored on his League début but was not retained at the end of the season. Outside of football Cowper was a Powderhall sprinter. His son-in-law is Jackie Wright, the Blackpool full-back who later managed Tranmere Rovers.