Others date it to when Mr Dyke was seen having breakfast with his old friend Sir Christopher Bland, chairman of the BBC governors, at a London hotel in January.
Certainly by mid-January, when Sir John invited the media to his annual drinks party, the only subject on everyone's lips was the battle for succession and the air was heavy with the crackle of prospective internal candidates eager to impress journalists.
Campaign managers were appointed who made sure that whenever their candidate made a pronouncement it was as widely disseminated as possible.
But it was also the campaign managers, rather than the candidates themselves, who leaked salacious gossip about rivals' drinking habits, drug-taking or disorganised working methods.
One candidate was supposedly a secret drinker while perhaps as many as two were supposedly about to be revealed as cocaine addicts by the News of the World.
But two weeks after the job was advertised and while head-hunters were interviewing prospective candidates the campaign entered a new phase when The Times unearthed an old story about Mr Dyke, who always was front- runner, donating pounds 50,000 to the Labour Party.
Mr Dyke's backing for the party in power sparked a political controversy, with the Tories insisting he could not be appointed.
The focus of the race moved to those working for and against Mr Dyke. The Times produced members of the great and the good who opposed Mr Dyke because they believed he would strip the BBC of its political impartiality.
Others, many who had worked with Mr Dyke at London Weekend Television in the Eighties, lined up to support him. In what now appears to have been a serious political miscalculation, William Hague, Conservative Party leader, joined The Times' campaign and came out publicly against the Pearson TV chairman.
Mr Hague's opposition to Mr Dyke was broadcast in The Times, which ran a front-page story under a now-unfortunate headline: "Hague to `veto' Dyke's bid for BBC job."
The Tory leader told the newspaper that it would be "totally unacceptable for anyone who has so substantially and recently supported a political party and even helped to fund the leadership campaign of a party leader to be appointed director-general of the BBC."
At the time, Tory officials believed Mr Hague's public intervention had effectively vetoed Mr Dyke.
Sir Christopher assured Mr Hague that the appointment would be impartial and free of political pressure "whatever the source".
The list was whittled by a panel of governors from 13 candidates to five: Mr Dyke, Alan Yentob, director of BBC Television, Tony Hall, chief executive of BBC News, Mark Byford, head of BBC World Service and Richard Eyre, chief executive of ITV.
The Times stepped up its campaign, and other newspapers voiced varying degrees of opposition to the idea of Mr Dyke as DG. It emerged that a group of as many as five governors were also opposed.
By the weekend Mr Yentob, the leading internal candidate was out of the race and the whole process, the longest in the BBC's history, was moving towards farce.
This week as the BBC presented its annual report to Parliament, the chairman of the Media Select Committee, Gerald Kaufman, was threatening to investigate the selection procedures of the BBC.
But on Wednesday night, after the presentation of the annual report to the press, the governors went to dinner together in London. They came to the decision by a small majority.
Tory sources said last night that Mr Hague accepted the governors' decision and would approach his talks with Mr Dyke in a constructive way.
However, senior Tories said privately that the party would be "watching the BBC like hawks" once Mr Dyke succeeded Sir John Birt. "I think the row will help us get a fairer crack of the whip, because he will have to bend over backwards to help us."
But Labour sources said Mr Hague's move had backfired and was another example of his poor judgement. "Relations will be frosty and the Tories could suffer," said a Labour MP. "Greg Dyke will not feel intimated by Hague. He will be his own man."Reuse content