The warning by Mr Greer to the Conservative Association will put renewed pressure on Mr Hamilton to stand down, in spite of local Tory defiance at the challenge by the "anti-sleaze" candidate Martin Bell, a former BBC war correspondent.
Mr Greer's intervention in Tatton on the eve of Wednesday's deadline for nominations will dismay Tory party leaders who had hoped that the sleaze row would subside. It will harden attitudes in the local Labour Party and in the Liberal Democrats, who meet tomorrow night to withdraw their candidates to back the independent Mr Bell.
Mr Greer on Wednesday will publish his account of the cash-for-questions affair in a book, One Man's Word. In an interview in today's Times, he says: "Neil Hamilton had been asked by Michael Heseltine, who was then President of the Board of Trade, whether he had had a financial relationship with Ian Greer Associates. Neil Hamilton answered 'No'.
"Neil Hamilton received commission payments from my company on two occasions. It was the killer blow for the trial."
Mr Hamilton's supporters assured Tatton activists that Mr Hamilton would have won the libel action with Mr Greer, and cleared his name if the case had not collapsed. Mr Greer says such assurances were misleading - intended to bolster Mr Hamilton's chances of re-adoption.Reuse content