[4] A southpaw, Dunn's professional career began with a win over Cardiff fighter Del Phillips in a heavyweight eliminator competition in Mayfair, London in July 1969.On 6 April 1976 Dunn won the European Heavyweight Title by a third-round TKO of the German boxer Bernd August at the Royal Albert Hall in London.His final fight was a fifth-round knock-out defeat to the South African boxer Kallie Knoetze at the Ellis Park Tennis Stadium in Johannesburg on 10 September 1977, after which Dunn retired from the sport.[6][7] However the future of the unused leisure centre is now in doubt, after Historic England granted the building Grade II listed status, following an appeal by the Twentieth Century Society.[8] After his sports career, having lost money in a failed hotel venture, Dunn lived in Scarborough, North Yorkshire with his wife Janet and three children, returning to work as a scaffolder.