David Cameron: I'll be 'disappointed' if Nick Clegg votes for mansion tax

David Cameron said he would be 'disappointed' if Nick Clegg voted in favour of a 'mansion tax' (Getty Images-)

Coalition tensions have escalated after David Cameron slapped down his Liberal Democrat deputy over the “mansion tax”.

The Prime Minister pointedly said he would be “rather disappointed” if Nick Clegg voted in favour of a levy on houses worth more than £2m.

Ed Miliband, the Labour leader, last week announced his support for a policy that has been a key Liberal Democrat commitment since 2009. But it is strongly opposed by the Conservatives and was not included in the Coalition Agreement.

To the irritation of the Tories, Mr Clegg and Liberal Democrat ministers have failed to rule out supporting Labour in a Commons vote on the issue next month.

Asked whether Mr Clegg had told him how his party was planning to vote, Mr Cameron told ITV News: “I haven’t asked him the question. But as it’s not in the Coalition Agreement to have a mansion tax, I would be rather disappointed if he did.”

Chancellor George Osborne has condemned the policy as a “tax con” and warned it would require inspectors assessing all the nation’s properties.

Mr Clegg retorted: “The Liberal Democrats have always been unambiguous that they want to make the tax system fairer. The Conservatives don’t want to do that. They don’t want, perhaps, to offend people in very large mansions.”

He has also accused Mr Miliband of “blatant plagiarism of Liberal Democrat ideas”.

Labour has proposed introducing the mansion tax to fund a new 10p starting rate of income tax.

It will call a Commons division on the proposal around the time of the Budget on 20 March in an attempt to exploit the strains within the Coalition.

Downing Street has already made clear that all ministers, including Liberal Democrats, would be expected to support existing Government policy. Sources said the contentious Labour motion would be modified to enable all Coalition members to support it.

Speaking in India, Mr Cameron made light of suggestions that Mr Miliband’s move could tempt Mr Clegg into a future coalition with Labour.

He said: “It’s enough running one coalition without trying to work out what another one would be”

The Prime Minister added: “I know I can work with Nick Clegg and deliver good governance for Britain. That’s what I’ve been doing for the last two and a half years.”