Coldwell signed for Sheffield United in 1951 from local side Norton Woodseats FC for a fee of £10.00, and although a late developer, played in over 600 matches for the Blades including 410 league games which included two rare goals! The captain of possibly the greatest Sheffield United team ever - the 1961 promotion team - he retired as a player in 1966. He joined the coaching staff at Bramall Lane, and was instrumental with the manager, John Harris, in their successful promotion in 1971 coaching world-class players, including Tony Currie and Alan Woodward. He had two stints as acting-manager in 1975 and 1977-78. Later he ran a newsagent's in Sheffield and Cheadle Hulme, before retiring to Poynton near Stockport.