McManus won his first wrestling title, the British Welterweight Championship, in 1949 by defeating Eddie Capelli for the vacant championship. He dropped the title to Jack Dempsey in 1957 but regained it from Dempsey. He dropped the title to him the following year, however. His 1963 bout against Jackie Pallo was watched by over 20 million people on British television. On 13 November 1967, McManus won the British Middleweight Championship with a victory over Clayton Thomson. Thomson regained the title in a rematch two months later. McManus also won the European Middleweight Championship in June 1968 by defeating Vic Faulkner. Faulkner regained the title belt in September, but McManus won it back in April 1971. He held the championship for almost seven years before losing it to Mal Sanders. McManus and Sanders traded the belt back and forth in matches that year and into the following year, with McManus holding the title a total of four times.