More than a quarter of a century after his death, John Lennon is still appealing to us to imagine a better world. The singer has been digitally resurrected in an advert asking people to donate laptops to the world's poorest children.

The former Beatle's voice and image have been stitched together using computers in a commercial for One Laptop Per Child, an organisation that aims to give low-cost, durable computers to young people in the Third World.

In the clip, multi-coloured pixels bombard the screen, eventually forming the face of the spectacled singer, who says: “Imagine if every child, no matter where in the world they were, could access a universe of knowledge.

"They would have a chance to learn, to dream, to achieve anything they want. I tried to do it through my music, but now you can do it in a very different way."

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His widow, Yoko Ono, has signed off on the advert, which will shown i America and on the internet. Lennon was shot and killed outside the Dakota building in New York, where they couple had a flat, in December 1980.

Ono has strictly policed Lennon’s legacy in the past, rarely allowing his image to be put to commercial — or even charitable — use. This has not stopped other Beatles and their music featuring in campaigns. Ringo Starr, the band's drummer, can be seen alongside the Hollywood actor Bruce Willis and the comedian Dame Edna Everage in a TV spot to communicate insurance company Norwich Union’s change of name to Aviva.

This year the music publishing company Sony/ATV, which owns most of the Beatles back catalogue, started to give advertisers permission use the Fab Four’s music in their campaigns.

The guardians of the Beatles songbook said that songs may be licensed for selected “brand partnerships” that enhance the original music’s reputation. Fans were outraged by one of the first deals, a campaign for Procter & Gamble’s Luvs nappies which proclaimed “All You Need Is Luvs”.

Before the nappy controversy, a small number of Beatles songs had been authorised for use in advertising campaigns but only if rerecorded by other performers.

Thanks to new technology, dead celebrities have made a habit of re-animating on to our screens to promote the latest products. Fred Astaire was seen dancing with a vacuum cleaner in an advert screened during the Super Bowl more than ten years ago, and Elvis Presley and the Muppets creator Jim Henson have also appeared posthumously in commercials.

The One Laptop Oer Child scheme is the brainchild of Nicholas Negroponte. He created a low-cost and long-lasting laptop with the aim of supplying one to every child in developing countries. The machines have built-in wireless internet connections and screens that are readable under direct sunlight, for children who go to school outdoors. They are also pre-loaded with software and books that children can share over the wireless connections.

Mr Negroponte approached governments and private sector corporations directly to buy and donate laptops. He also credited a scheme called Give One Get One that has just been started in Britain. For £275, consumers are given one of the laptops and another is donated to a developing country — or both computers can be donated.

Speaking to The Times, Mr Negroponte said: “It’s a window into the world that has an impact on whole villages. In the case of remote areas, we will drop a satellite dish in the centre of the village. That communicates with the nearest laptop which in turn connects with another laptop and that goes on for tens of miles.”

He said that the computers did more than educate children, they also benefit family members: “The kids brought their laptops home at night and were teaching the mother and father to read and write. It has this additional kind of impact.

“Children in most parts of the world are the objects of change. What we see is a village whose nature changes because the kids become the agents of change. That’s quite an astonishing change.”

By allowing Lennon's image to appear in adverts for the organisation, Ono has inidicated her strong support for the campaign. Critics of the concept argue that children in poor countries need books, food or mosquito nets to protect them against malaria rather than computers. Mr Negroponte disagrees saying that the issue is not appropriateness but whether these laptops can be used as a “substitute for education.”

The Give One Get One scheme began in in the United States in response to poor take0up by governments and has resulted in 100,000 donations to developing countries.

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