Lord Sainsbury of Turville, the former Labour science minister and the party's biggest financial backer, last night transferred £340 million of his shares in the supermarket group before this week's changes to the capital gains tax in a move which could save him £27 million.

The restructuring by Lord Sainsbury, whose family founded the Sainsbury's supermarket business, follows similar last-minute reshuffling of share portfolios by Sir Ken Morrison, the former boss at rival supermarket Wm Morrison, and by Sir James Dyson, the inventor and entrepreneur, before the controversial changes come into effect on Saturday.

The transfer was announced nearly two hours after the stock market closed last night.

Lord Sainsbury has moved the £340 million of J Sainsbury shares, placing 92 million shares in an investment vehicle he owns called Innotech Advisers and donating 8 million shares to his Gatsby Charitable Foundation.

This will allow him to pay CGT closer to the lower rate of 10 per cent before it almost doubles to 18 per cent. If he had sold the shares next week, he may have been liable to pay £61.2 million in tax rather than the £34 million he paid on last night's deal.

A person familiar with situation said: "The purpose is to preserve the same flexibility that exists today in the interests of Lord Sainsbury's intention, over his lifetime, to devote his personal wealth to philanthropy."

"There is no disposal of J Sainsbury shares and it has no impact on the Sainsbury family's ownership of shares in J Sainsbury plc."

The peer, who has donated more than £10 million to Labour, is one of Britain's richest men with his family's fortune estimated at £2.1 billion.

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