The decision to suspend her from the Scottish Parliament for a day had been taken by the Standards Committee, headed by Nationalist MSP Keith Brown. Two of his SNP colleagues – Christina McKelvie and Dave Thompson – sat on the seven-strong panel. Together with Lib Dem MSP Hugh O'Donnell, they won out against the votes of the three Labour and Tory members, arguing that Alexander should be punished.

At hand was the matter of whether Alexander should have placed a list of donations she received during the election campaign on to Holyrood's register of interests. An SNP researcher, Ian Fraser, had spotted that her failure to do so appeared to have flouted Holyrood's rules and thus put in a complaint to the Standards Commissioner, Dr Jim Dyer. Despite Alexander's plea of innocence Dyer took further advice and ruled that the cash did need to be registered.

Bitter claims were bouncing back and forth last night over the committee's behaviour. One Labour source said: "Keith Brown could easily have resolved this matter more quickly. There is a strong suspicion that they deliberately left it to the very last few hours of this parliamentary session to prevent the full Parliament from then voting on it. That ensured it would hang over Wendy for the summer."

Scotland on Sunday understands that had the full Parliament voted on the matter this week, and overturned the suspension, Alexander would have stayed on. Brown is prevented by the rules from commenting but a spokesman countered: "Labour's bitter accusations of partisanship simply repeat the negative attitude that saw Labour lose the Scottish Parliament elections and fail to develop as an opposition."

As for the dirty tricks campaign, Alexander's allies also point to the fact that another complaint has been issued to Dyer – from another SNP researcher– this time over a press release sent out by Alexander's press team about the Standards Committee report.

The rules state that MSPs are forbidden from talking about live investigations. SNP sources simply reply that the complaints are beside the point. The donations should have been registered – Alexander broke those rules and, therefore, was punished. End of story.

The bitterness within the Labour party about the complaints placed by the SNP researchers extended as far as her fiercest critics yesterday. "It has been utterly malicious, as simple as that," said one. But the same unanimity does not extend to the fact of her resignation. "This was stupid thing to resign over," said a senior source. "But the reality is that she did have a reason to resign."

The reasons are twofold. First there was the original mistake last year, when it emerged she had taken £950 from an off-shore businessman as part of her campaign fighting fund. "Either she knew it was wrong, or she wasn't aware," said another Labour figure. "Either way, she showed she didn't pass the leadership test."

An Electoral Commission investigation, which wound its tortuous way over the Christmas period, eventually cleared Alexander of "intentional wrongdoing", but the damage was done. Her credibility had been deeply damaged.

And second, there was her chaotic referendum U-turn. The details are now disputed. Team Alexander claims that the dramatic decision to commit Labour to a referendum on the break-up of the UK had been given the nod by Gordon Brown. It then claims that, after she had gone public, Brown lost his nerve, leaving her high and dry. But those close to the Prime Minister – and other senior figures – insist that he had done no such thing; that instead, she had simply acted on impulse.

Whatever the truth – and most people believe Brown – the row led to an irreparable rift between Alexander and the wider party outside Holyrood, effectively sealing her demise.

Senior Labour figures have effectively stopped trying to hold a line defending Alexander, complaining she only ever calls them up when she is in trouble or needs something.

A senior Labour figure complained: "She'll slag you off, but as soon as she needs something, she's on the phone demanding you help."

The dislike was mutual. The leader herself could be heard attacking Westminster colleagues openly for indulging in 'the black arts' against her. She insisted that she would never allow her aides to operate in such a manner. A huge rift between her team and the party's MSPs, and the Westminster Labour clique opened up. It could never last.

With her leadership credentials under pressure, Alexander could be heard arguing that only "Wendy Alexander" could have done all this. Andy Kerr, Iain Gray, Margaret Curran, Jack McConnell nor anyone else in the Holyrood group would never have had the necessary connections or strength to have both backed a referendum, and committed Labour to more powers at Holyrood, she boasted. She seemed oblivious to how by airing such claims, she did not appear strong, but insecure.

Yesterday, Alexander said the main reason for quitting was because she could no longer put the party through months more of innuendo and bad headlines concerning her donations.

While many of her critics in the party have sympathy for her, agreeing that she has been the victim of a witch-hunt, they will not lament her demise. The 10 months have confirmed what many already had suspected: that although Alexander may have one of Scotland's finest policy brains, when it came to the uniquely testing job of political leadership, she came up short.