Who did the fighter, who had vacated the British light heavyweight title that Dennis Powell won, defeat to become world middleweight champion ?
Dennis Powell (boxer):  He remained Welsh light heavyweight champion throughout his career and in 1953 he challenged for the British light heavyweight title vacated by Randolph Turpin, taking the belt after defeating George Walker. Randolph Turpin:  In 1951 he became world middleweight champion when he defeated Sugar Ray Robinson.
Sugar Ray Robinson.