The 64-year-old Anglo-French corporate raider lost his battle with pancreatic cancer three months after the anti-European Referendum Party which he founded made virtually no impact in Britain's general election, despite the pounds 20m of his own money he poured into it.
Sir James, whose complicated love life, complex business ventures and ownership of magazines kept him in world headlines for four decades, died of a heart attack at his farmhouse near Marbella, southern Spain, having recently moved there for quiet from his chateau in Burgundy as his illness worsened.
Sir James's wife, Lady Annabel, and mistress Laure Boulay de la Meurthe were with him when he died. The rest of his family, including ex-wife Ginette Lery and his eight children, among them Jemima Khan, remained at his French chateau.
Speculation will now focus on his will and the potential break-up of his vast estate. Sir James, worth - conservatively - pounds 1.5bn, had houses around the world, some lived in by his wife, former wife and mistress and their children.
Sir James was diagnosed as suffering from terminal cancer shortly before Christmas last year in Paris, and was given little more than six months to live.Only Lady Annabel, who lives at his home outside London, and Ms Boulay were informed of the seriousness of his condition.
Lady Annabel is understood to have wished him not to stand in the British election, where he fought David Mellor's seat in Putney. She was angry that the Referendum Party campaign was heavily criticised and that much of the attack was directed at her husband. During the campaign he collapsed on a helicopter trip and spent periods abroad receiving treatment. It was only when he was admitted to a clinic near Paris last month that his illness became widely known.
Sir James built a fortune from a series of business deals and takeover bids, but in recent years he had retired from business to campaign on environmental and other issues. He was no friend of the left and most tributes came yesterday from the political right. Lady Thatcher said: "Jimmy Goldsmith was one of the most powerful and dynamic personalities that this generation has seen.
"He was enormously generous, and fiercely loyal to the causes he espoused. He was a good friend and I am saddened by his loss." However, Tony Blair did find time to break off from Ulster concerns to comment: "He was an extraordinary character and although I didn't always agree with his political views, obviously, he was an amazing and interesting, fascinating man, and I think people will miss him."
Less complimentary was Richard Ingrams, former editor of the satirical magazine Private Eye which faced dozens of writs from Sir James. "He was one of nature's dictators," said Mr Ingrams. "His views were extremely right-wing ... I did not see anything to admire in him.
"The only thing in his favour was that he made a lot of money. His epitaph should be, 'He was extremely rich.' "
King with no country, page 16