He has played poker with Lord Lucan, been kicked out of Las Vegas for winning too much at blackjack and made a personal fortune of £90m from a spread betting firm founded with just £100.
Stuart Wheeler, the former chairman and chief executive of IG Index, is in many ways the ultimate gambler's gambler.
But, yesterday, the 67-year-old millionaire decided there was one outside bet even he could not risk making without being seen as a mug punter.
In a potentially fatal blow to Iain Duncan Smith's political career, the man who gave the Tories £5m before the 2001 election declared he would not donate a further penny until the party chose a new leader.
Mr Wheeler's scathing remarks could not have been made at a worse time for Mr Duncan Smith, with his poll ratings continuing to flatline, a parliamentary investigation being held into his office finances and backbenchers plotting against him.
The millionaire, whose donation to William Hague was the biggest cash gift to any British political party, appeared on BBC Radio 4's Today programme to deliver what could be the coup de grace to the Tory leader's increasingly faint hopes of clinging to his post.
Mr Duncan Smith must be thanked for developing new policies and ending the in-fighting over Europe, Mr Wheeler said. But the case for replacing him was "overwhelming" and Tory MPs had a "duty" to act urgently. "All one hears is that they [Tory MPs] all take the view that I have just expressed, or virtually all of them," he said. "That being so, not to be too pompous about it, it is almost their duty to have these 25 letters and get the thing going, and that is what I think should happen and very quickly."
Mr Wheeler was particularly scathing of recent attempts by spin doctors at Central Office to advise Mr Duncan Smith on how to improve his public speaking. Officials have dismissed claims that £100,000 was paid to image consultants but he has been coached in how to cure the frog in his throat, how to read an autocue and even how to make his hand gestures more assertive. All to little effect, Mr Wheeler said.
"I'm afraid my view is that he should go because, the crucial thing is, he is terribly bad at communicating," he said. "Instead of speaking naturally as his own man, perhaps as if one on one, he gives the impression that he has been taught how long to pause, what to do with his arms etc. So he doesn't come over at all as a potential Prime Minister. He comes over as weak. Therefore, he won't capture any significant number of Labour or Liberal Democrat votes."
Mr Wheeler's criticism of the leader's communication skills appeared prescient when, hours later, Mr Duncan Smith again failed to put up an effective performance at Prime Minister's Questions.
His similarly lacklustre performances at donors' dinners have, in particular, caused concern among senior figures in the party. With the party reliant on loans to keep it afloat, rumours that big backers have lost faith with the leadership are always a big factor for MPs looking for a further push to gather 25 names needed to trigger a contest.
Mr Wheeler made clear for the first time yesterday just how much of a deterrent Mr Duncan Smith was to possible donors. "I did happen to bump into one just the other day ... who is a previous big donor. I said, 'You gave lots of money?' He said, 'Not a sausage'."
He said Michael Howard, David Davis and Oliver Letwin could all do the job of leading the party "very well", before quickly adding: "I don't want to get into it. It's not for me to say." Money talks in the Tory party, though, and his views were seized on by many rebel MPs.
Tall, slim and impeccably polite, Mr Wheeler has certainly come a long way since he was born in Enfield, north London, to his unmarried mother.
He had a clubbed foot. He spent two years in an orphanage before he was adopted by Betty Wheeler and her husband, Alexander, a fairly well-off American. After Eton and Oxford, he started, then abandoned, a career at the Bar and had a chequered City career before founding IG Index in 1974 to allow punters to speculate on the price of gold. With the rise of sports and commodity spread betting, the firm grew into a money machine and he made £90m when it was floated in 2000.
He and his wife, Tessa Cod-rington, have three daughters and homes in London, Canterbury and Tangier, but Mr Wheeler is not a man of extravagance. Apart from his £5m gift to the Tories, his main indulgence is the $10,000 (£5,900) entry fee for the world poker championships in Vegas.
When William Hague, as Tory leader, received the huge donation without any strings before the election, he described Mr Wheeler as "like Father Christmas". Sadly for Mr Duncan Smith, Father Christmas appears to have turned into the Grim Reaper.
CHANGE OF HEART: CONSERVATIVES' LARGEST DONOR ON THE LEADERSHIP
On why he had decided to give the Tories £5m:
"I think William Hague would make a much better Prime Minister than Tony Blair. He's a man to get things done, with the interests of the country at heart."
17 January 2001
"Without wishing to sound arrogant, it's not a big sacrifice."
20 January 2001
"I admire Hague. He is straightforward and I hope he keeps the job after the election."
24 March 2001
On Duncan Smith:
"He doesn't come over at all as a potential Prime Minister.
He comes over as weak. My view is that he should go because, the crucial thing is, he is terribly bad at communicating."
22 October 2003Reuse content