Sir Alan Sugar sold his Amstrad empire to BSkyB yesterday in a £125 million deal that hands the star of The Apprenticea £34.5 million windfall.

Sir Alan and his senior management will join Sky under the acquisition, which comes 40 years after Amstrad first began to make consumer electronics.

His Essex-based company now generates about 75 per cent of its revenue by supplying the satellite television broadcaster with interactive set-top boxes, including Sky Plus.

Sky, which is 39.1 per cent owned by News Corporation, the parent company of The Times, said that the time was now right to buy Amstrad and bring its expertise in-house. It said that the move would help to bring down costs, provide control over product design and allow the company to speed up the delivery of next-genera-tion technology to subscribers.

Amstrad is understood to be working already on a new product.

The 150p-per-share offer, made through Sky’s Digital Supplies subsidiary, represented a 24 per cent premium to Amstrad’s closing price on Monday. The offer has already been accepted by Sir Alan and the board.

Amstrad shares leapt 21 per cent, or 26p, to 147.25p, after the bid was announced. Pace Micro, a rival set-top box supplier to Sky, fell 14p to 93.25p, but it is thought that Sky will continue to buy from other suppliers.

James Murdoch, the Sky chief executive, said: “Sky and Amstrad have had a long and positive relationship. The acquisition accelerates supply chain improvement and will help us to drive innovation and efficiency for the benefit of our customers.”

Sir Alan, who turned 60 in March, said that he could not imagine a better home for the Amstrad business. “Sky is a great British success story. I’m proud to have worked so closely with it, and I look forward to continuing to play a part in this exciting business,” he said.

The sale comes just a month after Sir Alan sold his remaining stake in Tottenham Hotspur, the Premiership football club that he once owned, for £25 million.

Despite a colourful business career, Sir Alan has become more well-known in the past two years for his starring role on the BBC show The Apprentice, where he tells unsuccessful contestants competing for a prize job: “You’re fired!”

After a brief spell in the Civil Service as a statistician after leaving school at 16, the entrepreneur set up Amstrad - Alan Michael Sugar Trading - at the age of 21. By the mid1980s it was one of Europe’s biggest consumer electronic companies after an ultimately doomed campaign to dominate the home computer market with the Amstrad CPC range.

In recent years the company’s fortunes have relied on the E-m@iler, a mass-market, fixed-line telephone that provided customers with e-mail and internet access. Amstrad conceded defeat by pulling out of the market last year.

It first made set-top boxes a decade ago and in the past year had supplied 30 per cent of the boxes bought by Sky.

As well as a rollercoaster ride in the business world, Sir Alan pioneered a wave of millionaires investing in football when he teamed up with Terry Venables, the former England manager, to buy Tottenham in 1991. He memorably condemned high-priced foreign players in English football as “Carlos Kickaballs” before standing down seven years ago and selling part of his stake in the club to Enic, the international sports entertainment business.

Yesterday’s move comes a week after Sky reported that the heavy cost of investing in broadband had cut full-year operating profits to £815 million, down 7 per cent.

James Murdoch was awarded 550,000 shares yesterday, worth £3.6 million at current prices, under a long-term incentive scheme.

The shares will vest in two years if performance targets are met.

Great shakes, big mistakes

— In 1984 Amstrad unveiled the Amstrad CPC 464, a distinctive matt black 8-bit home machine with a built-in cassette deck that soon outstripped its rivals - the Sinclair ZX Spectrum and Commodore 64. The choice between a green screen or colour monitor determined whether the price was £299 or £399. The series sold three million units in six years

— Amstrad has supplied set-top boxes to BSkyB since the pay-television group’s launch in 1989, when Sir Alan Sugar’s company was the only manufacturer producing receiver boxes and dishes. It is now a supplier of Sky+ boxes, which combine a digital video recorder and satellite receiver. Sky has sold more than two million of the units, which cost £99 as part of a subscription package

— In 2000 the £80 e-m@iler Phone was launched. It allowed users to send and receive e-mail without a PC. It may have been cheaper than a computer, but the device clawed back savings elsewhere: advertisements were displayed on the idle screen and users were charged 12p for every incoming message. One could be yours now for £6 on eBay.

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