Sir Alex Ferguson (L) and Roberto Mancini

Football historian Gary James has revealed that Manchester City and Manchester United considered merging in the 1960s. James states City chairman Frank Johnson made the proposal in 1964, but it was rejected by the United board.

"The idea was killed by both clubs before it ever became public," James was quoted as saying in a Daily Mail report. "I spoke to Eric Alexander whose dad Albert was chairman at the time, and he said Frank Johnson, who came up with the idea, often came up with crazy ideas."

At the time, James reveals, neither club was particularly buoyant. United were still recovering from the Munich air disaster of 1958 and looking to re-establish themselves as a top English club. Meanwhile, City were experiencing record lows in fan support and languishing in the second division.

"In 1964-65 we were in the second division, support had dropped to a low of less than 15,000, and general interest in the club had also dropped," he explained.

At the time, and this may be hard to believe, things were rather neighbourly between the two clubs. In the 1950s, Manchester United played their home games at City's old Maine Road ground while United's Old Trafford stadium was being rebuilt after wartime bombing. United used Maine Road again for its floodlights during European games in the 1950s.

Manchester City were promoted back to the old First Division (the precursor to the modern Premier League) in 1966. In 1967, Manchester United were crowned champions, followed one year later by City, who ended the season two points clear of United.

Nearly 50 years later, both Mancunian clubs have re-established themselves as English superpowers and top European clubs. City's 2012 Premier League title was the team's first in 44 years, and the rivalry between the two Manchester clubs is fiercer than ever.