As The Times disclosed yesterday, Mr Duncan Smith received a warning from Cabinet Office officials earlier this year about his use of the chauffeur driven Vauxhall Omega car he is given as leader of the opposition.

The Tory leader’s private office was reminded that the strict rules forbidding ministers from using their official cars for private or party political purposes also applied to Mr Duncan Smith.

A senior Conservative figure contacted The Times yesterday to say that the meeting in May came after a review of use of the Government’s car pool by the Cabinet Office which included examination of drivers’ logs.

This is understood to have shown Mr Duncan Smith had used his car for travelling to a Tottenham Hotspur football match, thought to have been against Arsenal last year, as well as taking his children to school. Other alleged breaches included travelling in the car to the Conservative Party spring conference in Harrogate.

Cabinet Office rules say that Mr Duncan Smith is entitled to free use of the vehicle only for duties arising from his role as Leader of the Opposition. The Conservative Party or Mr Duncan Smith himself would be expected to reimburse the Government for the cost of any journeys made for personal or party political purposes.

A spokesman for the Tory leader last night refused to discuss the issue saying: “As far as I am concerned the Cabinet Office has not said that there has been any breach of the rules.” Although the Cabinet Office has declined to discuss details of the case, spokesmen have confirmed that a meeting took place with Mr Duncan Smith’s private office to underline the rules in May. Government sources have also told The Times that the Tory leader’s aides received a “ticking off” at the meeting, where it was made clear that further infringements would not be tolerated.

The latest controversy over Mr Duncan Smith’s use of his political perks is particularly embarrassing because it comes amid the parliamentary inquiry into allegations that he improperly paid his wife, Betsy, from his Commons office costs allowance.

Many Tory MPs are waiting for the outcome of the inquiry by Sir Philip Mawer, the Parliamentary Commissioner for Standards, before deciding whether to renew efforts to oust Mr Duncan Smith from the leadership.

Stephen Gilbert, the Conservative Party’s director of campaigns, met Sir Philip yesterday to give evidence to the inquiry about Mr Duncan Smith’s private office arrangements.

Mr Gilbert, one of the party’s most senior officials, survived an attempt to sack him in February after being accused of having links to the Tory’s modernising faction. In a meeting with Sir Philip yesterday he is believed to have confirmed that he attended a number of meetings with Theresa May, the party chairman, at which concerns over Mr Duncan Smith’s use of his £64,000 a year common allowances were discussed.

Jenny Ungless, the Tory leader’s former chief of staff, is expected to make a witness submission today. There is growing speculation that Mrs May herself will be called to give evidence to the inquiry.

Mrs May is being touted by senior Tories as the likely casualty of a reshuffle planned by Mr Duncan Smith if he is cleared of all charges by Sir Philip’s report. Tim Yeo, the Shadow Trade Secretary, is said to have been lined up as a possible new party chairman.

Times Recommends

• Olympic-size television coming to your town
• Mosley opens new front in battle for privacy
• On-the-spot fine for man smoking in his van