Vincent Tchenguiz bought his 40-metre 12-berth yacht, his choice of name for the vessel was fitting

Vincent Tchenguiz bought his 40-metre 12-berth yacht, his choice of name for the vessel was fitting for a flamboyant property baron who, along with his younger brother, had bedazzled the City during the Noughties with fleet-footed acquisitions that acquired them the status and lifestyle of billionaires: Veni, Vidi, Vici.

Yesterday morning, Mr Tchenguiz was given the opportunity to contemplate the wisdom of borrowing Julius Caesar's supposed catchphrase – "I came, I saw, I conquered" – for his playboy accessory when he and his brother, Robert, found themselves answering questions from fraud investigators about their involvement with Iceland's Kaupthing Bank.
For two men who until the financial crisis had grown used to plotting ever-rising curves on their personal wealth graphs, the 6.30am wake-up call at their central London homes from City police officers was the latest stage in a two-and-a-half-year reversal of fortunes which has wiped £1bn off the value of Robert's business empire, and cost Vincent many millions.

The brothers built mighty portfolios with stakes in companies and properties valued at up to £4bn at the height of their success, pursuing cheap credit and an innovative approach to structuring deals (using rising rental rates to offset the cost of servicing loans before selling properties at a profit). Their investments covered an array of well-known names, including Odeon cinemas, Yates's wine bars, Slug & Lettuce and Hogs Head pubs, the tapas chain La Tasca and Somerfield supermarkets. They also had shareholdings in the supermarket giant Sainsbury's and the pub chain Mitchells & Butlers.

It would be foolhardy to write them off just yet. Both men issued a strongly worded denial of any wrongdoing while teams of police officers were still combing their offices close to the Dorchester Hotel in Mayfair.

Despite their reversals, the brothers, who were raised in Tehran as the sons of an Iraqi Jew before emigrating to Britain after the fall of the Shah, remain firmly within the auspices of the Establishment. R20, one of Robert's investment vehicles, has donated £53,620 to the Tories.

Veni Vidi Vici, the venue for the signing of many of Vincent's property deals, remained moored in Cannes ahead of a planned party tonight to coincide with "MIPIM" – the annual gathering on the Riviera for real-estate plutocrats and hangers-on.

There was no immediate word from the Tchenguiz camp as to whether either would still attend, but the presence of the yacht was meant to convey a clear message – that the brothers are still open for business, albeit with fewer zeroes on the end of their bank balances.

Noting Vincent's statement prior to the crash that business is "a game we want to win", one insider said: "Yes, times have been tough but what defines people is how they respond to a crisis. Do you disappear or do you stand up and start over again?"

Certainly, the brothers are not known for their dislike of the limelight. Throughout the 1980s and 1990s, they were fixtures on the upper end of London's party circuit. Such was their place among the glitterati, the story persists that Robert – better known as Robbie – was responsible for introducing Princess Diana to Dodi Fayed while staying on Necker Island, Sir Richard Branson's Caribbean hideaway. Friends have dismissed the matchmaking incident as apocryphal but both men have revelled in playboy reputations. Robert, junior to his brother by two years, dated the American model Caprice Bourret and celebrated his 40th birthday by converting his £30m mansion close to the Royal Albert Hall into a version of Louis XIV's Versailles, complete with liveried staff in pompadour wigs and a troupe of acrobats.

While Tchenguiz Jnr has stepped back from the public gaze, marrying the American anti-ageing entrepreneur Heather Bird in 2005, his brother shows little sign of abandoning his bachelor status.

Vincent, who spends his working day in front of 12 trading screens in the Mayfair office block raided by the Serious Fraud Office yesterday, reputedly owns 15 cars, including five Rolls-Royces, as well as houses in South Africa and the Cote d'Azur. He also reportedly won £1m by backing Greece to win the 2004 European football championship. When asked to compare his lifestyle with that of his younger brother, Vincent once said: "Slowing down, yes; settling down, never."