Peter Harrison

203 £206m Computer networks

Harrison, 66, worked as an accountant in the 1970s before buying Chernikeeff, a Surrey computer network company, for £133,000. In 1999 he sold 49.9% of it to a South African multinational for about £100m, and a year later he parted with the rest for £200m. A passionate sailor, he has spent more than £25m mounting British challenges in the America's Cup race. Huge gifts to charity have also clipped his fortune back.

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2003: £240m