The star of BBC's The Apprentice will make £35 million from the sale, but will remain with the Amstrad business under its proposed new owner.

Sir Alan founded Amstrad in 1968 and turned it into a household name after launching the first mass market home computer package in 1984. At its peak, the firm was valued at £1.25 billion.

The Brentwood-based company now generates around three-quarters of its revenues from the sale of set-top boxes to BSkyB, which has worked closely with Amstrad over many years. The broadcaster - 39.1% owned by Rupert Murdoch's News Corporation - said it would benefit from an in-house design and development capability.

Sir Alan said he could not "imagine a better home" for the Amstrad business, which supplied an estimated 30% of Sky's set-top boxes in the year to June 30.

He said: "I turned 60 this year, I've done 40 years of hustling in this business. I have to start thinking about my team of loyal staff, many of whom have been around me for a very long time."

Sir Alan said he did not think he was "letting go" of the Amstrad name by selling the firm, adding that he would still be involved. He told the BBC Radio 4 Today programme: "There's a certain culture there that will exist. It's not a case of letting it go, it's a case of moving the company on to something more positive."

Despite enjoying good working relationships, Amstrad said its directors recognised the "vulnerability" of relying on just two main customers - the other being Sky Italia.

It said the long-term future of Amstrad could be under threat from the potential loss of its largest customer, which would be difficult to replace.

Sir Alan is worth an estimated £830 million and ranked 84th on this year's Sunday Times Rich List, helped by his many property investments.