The biggest success of his career came on 29 May 1968 when the team won the European Cup. He retired as manager at the end of the following season, having announced his intention to do so on 14 January 1969, but remained at the club as a director, handing over managerial duties to trainer and former player Wilf McGuinness. When McGuinness was sacked in December 1970, Busby briefly returned to his managerial duties, but there was never any question of his returning as manager permanently. The job went to Frank O'Farrell in June 1971 after United were unsuccessful in approaching Jock Stein and Don Revie.