With his long limbs and delicate gait, Lord Mandelson could no doubt manage a quite convincing turn in Thunderbirds.

He'd find Jeff Tracy most convivial: a billionaire astronaut with his own Pacific island, and now, it seems, he even has his own camera-shy friend to pull the strings.

According to the High Court, Nathaniel Rothschild, scion of the banking dynasty and friend of seemingly everyone in the spheres of finance, business and politics, is indeed "puppet master" to the Baron of Hartlepool and Foy.

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The banker and Bullingdon boy has lost his libel case against the Daily Mail, which he sued for "substantial damages" over its account of his and Mr Mandelson's extraordinary trip to Russia in January 2005.

Mr Rothschild claimed he was subjected to "sustained and unjustified" attacks in the May 2010 article, which portrayed him as a "puppet master", dangling his friend Lord Mandelson in front of the Russian oligarch Oleg Deripaska to ease the passage of colossal business deals.

Messrs Rothschild and Mandelson's Russian trip would certainly have made entertaining viewing, but maybe not for Thunderbirds fans. Nobody needed rescuing, that's for certain.

It began on Mr Rothschild's private jet from the World Economic Forum in Davos to Moscow, where they met Mr Deripaska, the aluminium plant manager who became the richest oligarch of them all, and continued on Mr Deripaska's private jet to his chalet in Siberia, where "to beat jet lag" they were whipped with birch leaves before plunging themselves into icy water – a traditional Siberian banya.

Less salacious, but seemingly more sordid, was an earlier dinner at Cantinetta Antinori, a fashionable Tuscan restaurant in Moscow. Mr Deripaska, the Mail had claimed, was dining with executives from the US aluminium giant Alcoa, negotiating a £250m deal to buy two of Mr Deripaska's aluminium plants, at which a stumbling block was an EU import tariff on Russian aluminium. Enter Lord Mandelson, then a lowly Mister, but at the time the EU Trade Commissioner. The deal is done, costing several hundred British jobs, and the tariffs come down.

Mr Rothschild claimed the trip was "purely recreational", and Associated Newspapers had to admit during litigation that it couldn't be sure that Mr Mandelson had joined Mr Deripaska at dinner or whether aluminium tariffs were discussed, and in fact the deal had been struck before Mr Mandelson and Mr Rothschild arrived in Moscow. But for Mr Justice Tugenhadt, recreation it was not.

"So far as Lord Mandelson was concerned the benefit was the trip and the hospitality itself. So far as Mr Deripaska was concerned it was a relationship with the EU Trade Commissioner," he said in his ruling. The judge rejected the notion that Mr Rothschild and Mr Mandelson had flown out as friends, not business associates, and said Mr Rothschild's behaviour had in part been "inappropriate". "That conduct foreseeably brought Lord Mandelson's public office and personal integrity into disrepute," the judge said.

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Mr Rothschild's "different and developing" accounts of the Siberia trip were confusing, he continued, adding that on this subject the banker had not been entirely candid.

Mr Rothschild said he was disappointed with the judgement and intended to appeal. "The truth is, as the Daily Mail has now accepted, that I had nothing whatsoever to do with this deal and that it had in any event been completed before Lord Mandelson and I even arrived in Moscow," he said in a statement. Disputing the judge's findings, he added: "Lord Mandelson's trip to Russia was entirely recreational – as the court has accepted – and Lord Mandelson had obtained clearance for the trip from his office before undertaking it."

Puppet masters, of course, do not like the limelight, but when one pulls quite as many strings as Mr Rothschild would appear to, things will inevitably go wrong. Indeed, it is not the first time this seemingly unlikely trio has conspired to make the headlines. When Mr Deripaska moored his yacht next to the Rothschild family villa in the summer of 2008, they, along with George Osborne, managed to tie themselves up in an even more spectacular imbroglio.

Either on the yacht or in the villa, Lord Mandelson might have said unkind things about Gordon Brown and Mr Rothschild is alleged to have suggested that Mr Deripaska might be interested in making a donation to the Tories. Via the two politicians it all ended up in the press – the last place their two hosts like seeing themselves.

That leading politicians, bankers and businessmen associate with each other in fashions that blur the boundaries between work and pleasure is a secret too great to be maintained with any success, but it doesn't make the details, on the rare occasions they actually emerge, any more palatable.

A spokesman for the Daily Mail said: "This case is a reminder, at a time when newspapers are under attack for invading privacy, that the rich and powerful regularly use the law to prevent legitimate scrutiny of their activities. Had the Mail lost this case, it could have incurred costs of more than one million pounds.

"Not many news organisations, however committed they are to free speech, can afford to risk a loss of that magnitude. As Lord Justice Leveson's inquiry considers the balance between privacy and freedom of expression, the chilling effect on free speech that court cases like this one exert needs to be borne in mind."