By Brian Wheeler
Political reporter, BBC News
Clare Short's decision to quit the Labour whip has left many people scratching their heads at the thinking behind it.
It may give the former international development secretary even more freedom to attack Tony Blair's foreign policy and leadership style.
But it will also marginalise her still further in the eyes of potential allies and, arguably, the media.
She may also find it a struggle to find supporters for her latest crusade - to shake up Britain's voting system, even though electoral reform is creeping back up the political agenda (Peter Hain is expected to make it a key plank of his campaign for Labour's deputy leadership).
Already shunned by many left-wing Labour MPs over her support for the Iraq war - she only resigned after the invasion had taken place - Ms Short is now being branded a "traitor" by the loyalist wing of the party.
And, needless to say, there will not be an alliance with Respect MP and fellow Labour exile George Galloway any time soon.
Ms Short is certainly not alone among Labour MPs in feeling the government has become "arrogant" and that it has lost touch with traditional Labour values.
But what will anger many on the backbenches is that, rather than stay and fight for change, she has simply walked away.
Another former minister, Peter Kilfoyle, earlier this year told the BBC News website that Labour's 2005 manifesto was a "pig in a poke" foisted on MPs at the last minute.
But Mr Kilfoyle, who quit the government over the Iraq war, spoke for many when he expressed bemusement at Ms Short's latest move.
"I would ask what she hopes to achieve by resigning. No matter how strongly you feel about issues, you should stay inside the party and fight your cause.
"She voted for the war, and I never understood the logic of voting for the war and then resigning from the Cabinet. I do not understand why she has taken the line she has."
Ms Short's belief in the virtues of a hung parliament - apparently the reason for her final split from the parliamentary party - has also led to a few puzzled faces around Westminster.
The opinion polls currently suggest an electoral tie - with no one party able to command a majority - is the most likely outcome at the next general election.
But how you would go about campaigning for such an eventuality is hard to fathom.
In her resignation letter, Ms Short explains that she would see a hung parliament as an opportunity to push the case for electoral reform.
What is needed, she argues, is a shake-up in the voting system, so that "the House of Commons more accurately reflects public opinion and we have a parliament more able to hold the government to account and to ensure that policy is well considered".
Not for the first time in her career, Clare Short is speaking from the heart. The question is, will anybody listen?