Plot to ditch IDS by time of Queen's Speech

Leading Tories have calculated that Iain Duncan Smith will have been ousted from the party leadership before the Queen's Speech on 26 November, leaving his deputy, Michael Ancram, to face Tony Blair on one of the two most important occasions in the parliamentary calendar.

One forecast yesterday that letters from MPs calling for a vote of confidence in Mr Duncan Smith will "fall like snow" once the Parliamentary Commissioner for Standards has completed his investigation into the salary the Tory leader paid his wife, Betsy.

Others want to strike before Sir Philip Mawer has delivered his report, arguing that the Tory leader should be removed for political reasons, and that the allegations about his wife are an irrelevance.

About 12 Tory MPs are thought to have written already to Sir Michael Spicer, chairman of the backbench 1922 Committee. As soon as that figure reaches 25, Mr Duncan Smith will face a vote on his future by his fellow MPs, which would almost certainly end his leadership.

A Tory former government whip predicted: "In the next three weeks, everything will become much, much clearer. He will be out within a week of the 25th letter. There is no chance that he will still be here for the Queen's Speech."

The Commons debate after the Queen's Speech is one of the two big set-piece occasions in which the Leader of the Opposition delivers an indictment of the Government's record over the previous year, the other being Budget day. Assuming Mr Duncan Smith has been removed from office, Mr Ancram, as deputy leader, will take over as his temporary replacement until an election has been completed.

In addition to the MPs who have written to Sir Michael, one of the party's longest-serving MPs, Sir Patrick Cormack, has written to the Tory leader personally, appealing to him to subject himself voluntarily to a confidence vote. Sir Patrick told BBC Radio 4's Today programme: "The fact of the matter is there are those from the Shadow Cabinet down who are not happy with what is going on ... It would be completely dishonest to say he has the united support of a united party in Parliament."

Many of the MPs actively pushing for Mr Duncan Smith's removal have been exasperated by the allegations about the £15,000 he paid out of public funds to his wife, Betsy, because they say it is irrelevant to the case against, which concerns his ability to lead the party rather than his personal integrity.

Edwina Currie, a former minister, says in an interview broadcast today that Mr Duncan Smith should not have been elected leader. She tells Granada's Sunday Supplement: "I wish that he had never existed. I wish he had never plagued the party in the first place."

The former Tory MP Matthew Parris wrote in yesterday's Times that Mr Duncan Smith should be sacked immediately. "I appeal to my former colleagues to understand that the moment is now, that it may not come again, and that it must be seized," he said.