Greek islands and Russian oligarchs
A Greek villa, an oligarch's yacht and Peter Mandelson combined in 2008 to undermine the 30-year friendship between shadow chancellor George Osborne and financier Nat Rothschild.
George Osborne and Nathaniel "Nat" Rothschild became friends in the late 1970s when they started at Colet Court, the feeder school for St Paul's. Osborne moved on to St Paul's at 13 while Rothschild went to Eton, but the duo were reunited a few years later at Oxford University, where their friendship flourished – not least through their membership of the infamous Bullingdon Club. 
After Oxford the two remained friends, though they took somewhat different paths. Nat Rothschild enjoyed several more years of Bullingdon-style antics, accompanied by reports of strained relations with his father, who it was said worried that his son would never settle down. Osborne, meanwhile, buckled down and focused on his political career.
By the time the pair were holidaying at Rothschild's Corfu villa in August 2008, Osborne had become Tory shadow chancellor and Rothschild had turned his life around. A key figure at leading hedge fund Atticus, Rothschild had done so well he was tipped by the Sunday Times Rich List to become the richest Rothschild in a generation.
But Osborne and his family were not the only guests of the multi-millionaire financier. Also visiting were Lord (Peter) Mandelson, then EU trade commissioner, and Russian oligarch Oleg Deripaska, who'd moored his £80m yacht off the coast. Rothschild is reported to have started his friendship and subsequent business relationship with Deripaska in 2002, and among other things the pair were jointly involved in a plan to build a major marine port in Montenegro. 
It is said that Rothschild, due to lack of space in his luxury villa, asked Deripaska to give Mandelson a bed on the Russian magnate's yacht. Moored nearby was a Murdoch family yacht where the clan and friends were gathering to celebrate Elisabeth Murdoch's 40th birthday. Over a number of days various gatherings took place, not least one now infamous evening in a Greek taverna when Mandelson was reported to have "dripped poison" about Gordon Brown into the ear of Osborne.
When parliament returned, and just days after Mandelson made his own personal return to the government as business secretary, Osborne leaked details about Mandelson’s thoughts on Brown to the press. He also revealed Mandelson had stayed on Deripaska’s yacht. With Deripaska's significant business interests in Europe, the relationship with Mandelson was slammed as a conflict of interest. A political storm ensued.
As the architect of the meetings, Nat Rothschild was furious with Osborne for slighting his friends Mandelson and Deripaska, and sent a damning letter to the Times alleging that George Osborne had tried to solicit (an illegal) £50,000 donation for the Tory party from Deripaska. 
Rothschild’s letter stated: "Not once in the acres of coverage did you mention that George Osborne, who also accepted my hospitality, found the opportunity of meeting with Mr Deripaska so good that he invited the Conservatives' fundraiser Andrew Feldman... who was staying nearby, to accompany him on to Mr Deripaska's boat to solicit a donation… Since Mr Deripaska is not a British citizen, it was suggested by Mr Feldman, in a subsequent conversation at which Mr Deripaska was not present, that the donation was "channeled" through one of Mr Deripaska's British companies. Mr Deripaska declined to make any donation."
Both Osborne and Feldman denied this claim. 
For the time being, their friendship was over.
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