As Sir Alex Ferguson announces his retirement as Manchester United manager, Dan Walker is joined by Robbie Savage, Dion Dublin and Steve McClaren for a special Football Focus looking back on Sir Alex's career. During his 25 years in charge at Old Trafford, United have won an incredible 38 trophies, making the Scot the most successful manager in English football history. Featuring contributions from Alan Shearer, Alan Hansen and Michael Owen and look back at Ferguson's recent in-depth interview with Football Focus. Show less