Lord Ashcroft, the deputy chairman of the Conservative Party, has bought majority stakes in two influential political websites, prompting the editor-in-chief of one of them to resign.

ConservativeHome, a Tory website representing the voice of the party’s grassroots, and PoliticsHome, which publishes political research and stories from across the web, are now 57.5 per cent owned by the peer who oversees the Conservative Party’s “target-seat” campaign. Both sites receive around a million hits a month.

Andrew Rawnsley, The Observer’s political commentator, announced his resignation as editor-in-chief of PoliticsHome, saying that the new ownership meant it was no longer possible to have confidence in the website’s political independence. He said that he was disappointed with the decision to sell by Stephan Shakespeare, who created the site 18 months ago.

ConservativeHome was set up in 2005 by Tim Montgomerie, Iain Duncan Smith’s former chief of staff, and has become hugely influential as a critical friend of the party. As well as in-depth news about Tory affairs, the site runs campaigns, often from a socially conservative, activist standpoint, sometimes clashing with the modernising instincts of the party leader, David Cameron.

It has also raised questions over Lord Ashcroft’s role in the Conservative Party, running a survey last month which found that 62 per cent of readers believed that the peer should pay tax in Britain. He gave assurances that he would live in the UK before receiving his peerage in 2000, but his domicile for tax purposes here has never been established.

The site had already made clear that it would become less critical of the leadership as an election approaches, in order to give Mr Cameron the best chance of winning.

Mr Montgomerie said: “I have been given solid assurances by Michael that he does not wish to interfere with ConservativeHome’s editorial policy in any way. I am completely satisfied with those assurances and am delighted that such a major figure in the Conservative Party is willing to invest in the future of this website.

“The proof of the pudding is, as always, in the eating and I hope you’ll see ConservativeHome and related initiatives go from strength to strength.”

Lord Ashcroft, who runs the Conservative Party’s marginal-seat campaign, was knighted for his services to Belize. His company, Bearwood Corporate Services, has given the party £3.95 million in cash and polling fees since Mr Cameron was elected as leader, although it is not clear whether he is eligible personally to make donatations because he does not appear on the public version of the electoral roll. Bearwood is currently under investigation by the Electoral Commission.

He already part-owns Total Politics, the advertising-funded political magazine that takes a neutral line and is published by Iain Dale, the Tory blogger. Mr Shakespeare will be the main minority shareholder and chairman in the new company.

In a statement on the website, he said: “PoliticsHome will remain strictly non-partisan and readers can continue to have absolute confidence in its editorial independence.” PoliticsHome said yesterday that it would use a £1.3million cash injection to make the site more useful for businesses.

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