Supermarkets are the latest fare for the Tchenguiz family. Robert, 46, has spent about £450m acquiring a 5% stake in J Sainsbury, the supermarket giant. American- born Bird-Tchenguiz is said to have tamed her husband, who previously had a reputation as a champagne-swilling playboy, linked romantically to Princess Diana and the model Caprice. But barely a week goes by without Robert or his brother Vincent, 50, buying or selling as they develop their diverse property portfolio. Britains most frenetic dealers in business assets, the brothers set up Rotch Property Group in 1982, dealing in flats in London, and never looked back. Today they control assets worth more than £4 billion, according to Vincent. They are part of a consortium that in 2002 paid £327m for Shell-Mex House, the art deco offices by the Thames, which is for sale with a £550m minimum price tag. Last year they sold 180 Shell petrol stations for £460m, six years after buying them for £300m. And so it goes on. Between them the brothers have 486 directorships, although since 2003 they have pursued separate investment strategies. Robert now runs R20, while Vincent invests through his Consensus Business Group. Robert has invested in pubs, health clubs, supermarkets and, with his brother-in-law, Vivian Imerman (qv), the Scottish whisky group Whyte & Mackay. Heather is an anti-ageing visionary with clinics in Harley Street and Knightsbridge, while Vincent is looking at green investments. We can see £763m of net assets held by various Tchenguiz companies. Private assets and profits on property sales should help take them to £850m. This may be below the Tchenguiz internal valuations but we are mindful of their borrowings.