“With the focus on open and transparent party funding, it is high time Lord Ashcroft said publicly whether he is fully resident and domiciled in this country for tax purposes, whether he pays UK income tax on all his UK earnings outside the UK and whether he has now complied with the assurances he gave as a condition of receiving a peerage and therefore a place in Parliament.

“To vote on this country’s laws you must pay tax in exactly the same way as the overwhelming majority of your fellow citizens. No representation without taxation should be our principle today.

“I have written today to Lord Ashcroft asking him to put the record straight and I look forward to a full and early response.

“In the light of Conservative comments about the need for openness, I have copied my letter to David Cameron asking him to ensure that Lord Ashcroft, as vice-chairman of his party, stops the secrecy about his tax status and comes fully onshore now if he still has not done so.”