During the libel trial George Carman, Mr Fayed's QC, was refused permission by the judge, Mr Justice Morland, to tell the jury that Mr Hamilton was being backed by "a group of millionaires".
The "Neil Hamilton Fighting Fund" is run by Lord Harris of High Cross, a former president of the Institute of Economic Affairs (IEA) and Norris McWhirter. Among those who have given money are Taki Theodoracopulos, the Greek socialite, the former Tory MP and whip Gyles Brandreth and the Tory MP Gerald Howarth. Another donor is Tiny Rowland's widow, Josie.
In court supporting Mr Hamilton were Edward Leigh, once Baroness Thatcher's under-secretary of state at the Department of Trade and Industry, and Derek Laud, a black member of the right-wing Monday Club.
They all share a common belief that Mr Hamilton had been unfairly treated by the system, and a loathing for Mr Fayed, whose sleaze allegations did much to bring down the last Conservative government.
The fund has raised pounds 410,000 from contributions that ranged from pounds 500 to pounds 10,000. Mr Hamilton claimed it was run on the lines of a blind trust and he did not know who contributed. If he lost the trial, he said he would file for bankruptcy.
It is the second time that Lord Harris had run such a fund for the former MP for Tatton. In the mid-Eighties he successfully sued the BBC over a documentary, Maggie's Militant Tendency, which suggested that the Conservatives were experiencing entryism from the extreme right.
Lord Harris said: "I remember at the time Neil came to me and raised the question of financing the libel action. I managed to raise around pounds 100,000, enabling Neil at the time to go after the BBC. Neil had a similar problem over Fayed. He came to see me, and Norris and I set up the fund. I have made a contribution, and others are a combination of donations and pledges."
Lord Bell, Lady Thatcher's former PR adviser, said: "I have made a pledge to contribute, but have not done yet. I wanted to help because Neil is an old friend and many of us feel that he has received a very thin end of the wedge ... He got the blame when others were doing very similar things."