Twitter has reported that 1.4 million tweets relating to the retirement of Sir Alex Ferguson have appeared on the site within an hour of Manchester United announcing the news.

Alex Ferguson retires
Alex Ferguson celebrates Manchester United clinched the Premier League title with a win against Aston Villa at Old Trafford, April 22, 2013. (Credit: Reuters)

In a blog post, the micro-blogging site said that the original tweet from Manchester United's press office announcing Ferguson's retirement had been retweeted 18,000 times an hour after it was originally sent at 9.18am. The story's official hashtag, #ThankYouSirAlex, had also been used 100,000 times in the first hour after Ferguson's retirement was announced, ranking number four on the list of 10 topics currently trending on Twitter worldwide.

Another popular tweet, gathering 13,000 retweets so far, came from the captain of arch-rivals Manchester City, Vincent Kompany, who wrote: "Sir Alex, one of the best managers of all time. After 26 years of success in the game, we all owe him a tribute." Prime minister David Cameron also paid tribute to Ferguson's career on Twitter, writing: "Sir Alex Ferguson's achievement at #MUFC has been exceptional. Hopefully his retirement will make life a little easier for my team #AVFC."

US President Barack Obama's "four more years" tweet following his election victory in 2012 is so far the most popular tweet ever, garnering more than 805,000 retweets and being favourited 300,000 times. A tweet from Justin Bieber eulogising a young fan was also honoured in Twitter's "Golden Tweets" awards last year, gathering 226,000 retweets and 100,000 favourites.

Sir Alex Ferguson departs from Manchester United after serving as manager for 27 years. Since joining in November, 1986, he has guided the club to win 28 major trophies and 13 Premiership titles.

"The decision to retire is one that I have thought a great deal about and one that I have not taken lightly," Ferguson said. "It was important to me to leave an organisation in the strongest possible shape and I believe I have done so.

"To the fans, thank you. The support you have provided over the years has been truly humbling. It has been an honour and an enormous privilege to have had the opportunity to lead your club and I have treasured my time as manager of Manchester United."

Ferguson will now become a director at Manchester United Football Club. Everton' David Moyes is among the favourites to take over as manager.

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