Alex Ferguson’s shock retirement today drew tributes from across the political and sporting spectrum.

British prime minister David Cameron, who supports Aston Villa, also paid tribute by tweeting: “Sir Alex Ferguson’s achievement at #MUFC has been exceptional. Hopefully his retirement will make life a little easier for my team #AVFC”.

Labour leader Ed Miliband tweeted that Ferguson was a “Proud man. Great manager. Staunch Labour Party supporter”, adding that he “will never be forgotten”.

Former United striker Dwight Yorke, who played under Ferguson between 1998 and 2002 and was part of the 1999 treble-winning side, feels a combination of factors led the Scot to call it a day at the age of 71.

“I’ve seen Sir Alex Ferguson on Monday at a charity game,” the former Trinidad and Tobago international told Sky Sports News.

“He was in good spirits but the rumours were really strong around the place that he was going to retire and there was a big announcement supposed to be happening tomorrow and not today.

“I think probably the fact of the club floating on the stock market meant this decision needed to come out very quickly. But the people within the football club knew this was likely to happen this season. And I think with his hip replacement (booked in for late July), with David Gill going as well, that sort of pushed him to say ‘this might be the best time for me to retire’.”

Joel Glazer, joint chairman of the Manchester United board with brother Avie, pinpointed the 2008 Champions League final penalty shootout success over Chelsea as a highlight among the many memories. He said: “Alex has proven time and time again what a fantastic manager he is but he’s also a wonderful person. “His determination to succeed and dedication to the club have been truly remarkable. I will always cherish the wonderful memories he has given us, like that magical night in Moscow.”

Fifa president Sepp Blatter, who gave Ferguson with a lifetime achievement award last year, said on Twitter: “Just heard Sir Alex Ferguson is retiring at end of season. His achievements in the game place him without doubt as one of the ‘greats’.”

Professional Footballers’ Association (PFA) chief executive Gordon Taylor said Ferguson would be “the toughest act to follow”. Taylor told Press Association Sport: “The game of football will be a lot poorer place without him. He has been quite simply the best. He followed in Sir Matt Busby’s footsteps and even surpassed him. “He will be also be the toughest act to follow.”

British sports minister Hugh Robertson also paid tribute, saying: “Sir Alex

Ferguson is one of the greatest British managers of all time and has been an incredible servant to Manchester United, bringing the club unprecedented success domestically and in Europe. “His enthusiasm for our national game is boundless and I congratulate him on a remarkable managerial career.”