The Sunday Times has won an Appeal Court decision which means it can now defend at trial a libel action brought by Peter Cruddas.
The Court of Appeal has overturned a ruling that the former Conservative co-treasurer had won his action against the paper.
The case will now go to trial after Lord Justice Longmore restored the defence of justification. He also lifted the injunction preventing publication of the allegations.
On 5 June, Cruddas was told he had won his case, which he brought over an allegation about charging £250,000 to meet David Cameron.
The Sunday Times said immediately that it would be applying for permission to appeal the decision by Mr Justice Tugendhat.
Cruddas, 59, sued Times Newspapers Ltd and two members of the newspaper's Insight team for defamation and malicious falsehood over three articles which appeared in March 2012.
Last year’s Cruddas allegations appeared after the journalists pretended to be agents for foreign investors who wanted to explore making donations to the party and hired a lobbyist, through whom they arranged to meet Cruddas. Each reporter carried a concealed camera with an audio recording facility.
Cruddas complained the articles meant that, in return for cash donations to the party, he corruptly offered for sale the opportunity to influence government policy and gain unfair advantage through secret meetings with the Prime Minister and other senior ministers.
He also said they meant he made the offer even though he knew the money offered for meetings was to come, in breach of the ban under UK electoral law, from Middle Eastern investors in a Liechtenstein fund.
The newspaper took issue with the meanings claimed by Cruddas, pleaded justification on alternative meanings to the libel claims, and denied the articles were false or published maliciously.
But Mr Justice Tugendhat ruled in Cruddas's favour on meaning, struck out the justification defence and entered judgment for him on the defamation claim, with damages to be assessed.
A spokesperson said: “The Sunday Times welcomes the decision and will continue to defend its undercover journalism and the public interest report about cash for access to David Cameron.”