If ever you wonder in a philosophical moment what rich men are for, Lord Sainsbury of Turville supplied an answer yesterday.

He didn't care for CVC's plans for what used to be his family firm, so he saw them off. That cost him, personally, a windfall worth the best part of #1 billion - plus the undying resentment of all the fund managers, bankers, brokers and lawyers who now miss out on the Himalayan fees and bonuses that go with a #10 billion deal.

David Sainsbury decided that if the private equity merchants passed the debt they were raising for the purpose through to Sainsbury's balance sheet it would undermine the company. To achieve the "tax efficient" structure it wanted CVC needed acceptances from holders of 75 per cent of the shares, which Lord Sainsbury, his family and allies were able to deny it.

The gearing proposed by CVC would also have had consequences for the pension fund, whose trustees must have had a hand in yesterday's events. It would be interesting to know what accounting formula they used to calculate their deficit in these negotiations.

Unlike a fund manager who is judged by his latest quarterly performance, Lord Sainsbury is rich enough to take a medium-term view. He reckoned that Sainsbury's chief executive, Justin King, should be given time to finish the excellent job he has begun.

Even in Blair's Britain, where a millionaire is someone paid #1 million a year, it is rare to see personal wealth used to such decisive, principled purpose, uniquely so when the immediate effect is to reduce an individual's wealth.

Whether events prove Lord Sainsbury right or wrong - we shall see what now happens to Sainsbury's properties, reputedly worth much more than the stated #7.5 billion - it has been an edifying spectacle.

Yet there is one strange aspect to this. Sainsbury was not seen as a bid target until it reported in February that the Sainsbury family had reduced its total stake by three per cent, 52 million shares. Forty million of those came from from the "blind" trust, which held Lord Sainsbury's shares while he was a member of the Government as Science Minister. Through all his years in government, this trust made no move to diversify so as to lower the inherent risk of owning 16 per cent of a supermarket company that had its ups and downs.

True, the shares had recovered handsomely as Mr King's magic started to work. There was a perfectly good investment case for saying it was time to lock in some of this recovery. That said, the family shares were sold for an average of 385p and this week Lord Sainsbury has insisted that nothing short of 600p could be acceptable.

The message that went out, no doubt unintentionally, that the Sainsbury family were potential sellers. The genie was out of the bottle. We shall now see whether the formidable Lord Sainsbury has put it back there for keeps.

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