By Ian Dunt
Labour is demanding the resignation of Michael Ashcroft as the row over his non-dom status threatens to engulf the Conservatives.
Lord Ashcroft confirmed his tax status after a decade of mystery on Monday with a statement on his website.
But yesterday Labour stepped up its attack on the Tory donor, with Harriet Harman and David Miliband demanding his resignation and a statement from David Cameron explaining what he knew and when.
It emerged today that Mr Cameron found out about Lord Ashcroft's status a month ago, putting him at odds with shadow foreign secretary William Hague, who told the BBC he found out "over the last few months".
The revelation raises serious questions about communication in the upper echelons of the Conservative party, with commentators asking how Mr Cameron and his unofficial deputy could fail to tell each other such pivotal details about the funding behind their general election campaign.
"At a press conference in December 2007 David Cameron said that he had asked Lord Ashcroft and was given the 'reassurance that the guarantees he made at the time are being met'," said Peter Mandelson.
"Yet this afternoon Liam Fox is saying on David Cameron's behalf that he only found out about Lord Ashcroft's status 'within the last month'.
"So either David Cameron was misleading the British people in December 2007, or he was being misled by Lord Ashcroft. The question for David Cameron this afternoon is which is it?"
The Conservatives were relieved to get a clean bill of health from the Electoral Commission earlier today however, which found that donations from Ashcroft's Bearwood Corporate Services company were legitimate.
But the report from the commission seemed to criticise the Tories for refusing requests for interviews while it was conducting the 18-month investigation. The Tories hit back saying they had replied to the requests but never heard from the commission.
Mr Hague, Tory leader when Lord Ashcroft's peerage was granted, confirmed on BBC Radio 4 last night that the donor had succeeded in converting his pledge of 'permanent UK resident' - the demand made by a Lords scrutiny committee - into that of a 'long-term resident', a lesser commitment which still allowed him to be a non-dom.
A letter from Mr Hague to then-prime minister Tony Blair revealed he assured Mr Blair that Lord Ashcroft was "committed to becoming resident".
But last night Mr Hague admitted: "Over the last few months I knew and, after that, of course I was very keen to support him in making that position public."
His opposite number, Mr Miliband, responded by saying Lord Ashcroft's position had become "untenable".
"They have known that in fact Lord Ashcroft was a non-dom, but they have not seen fit to tell the rest of us," he told the BBC.
Andy Burnham, health secretary, told Sky News it was "implausible" to suggest Mr Hague was unaware of the tax arrangements.
"I certainly think the Tories have got a lot of questions to answer as we find out about this whole saga," he said.
"I find it very implausible that William Hague didn't know for ten years."
During PMQs yesterday, Ms Harman said: "We cannot have it that both the vice chairman of the Conservative party is right and the shadow foreign secretary is right.
"One of them should go."
This morning, Gordon Prentice revealed on his blog that the Commons public administration committee will be launching a one-off inquiry into the affair and inviting Lord Ashcroft to come speak to it as part of the investigation.
In a separate move, the Lib Dems are demanding HM Revenue and Customs investigate whether the commitment to 'permanent residence' is compatible with Lord Ashcroft's non-dom status.