In at No 26, the pop group who have an average age of 78

The Zimmers, a newly formed group who have a combined age of 3,000 years, were celebrating a musical triumph last night with a top-30 entry into the UK's official singles chart.

They might make the Rolling Stones look like a bunch of young upstarts, but the 40-strong band, with an average age of 78, entered the charts at No 26 with their debut "My Generation", a cover of a single by The Who.

The entry is more surprising as the group were not on any playlists, probably because they "were not young and trendy enough" according to one of the group's associates, who said he was confident that they would break into the top 10.

The lead vocals were sung by Alf Carretta, who is 90 years old, but still a mere stripling compared to Buster Martin, 100, the drummer, who still has plenty of rebelliousness in him. At the end of the video he sticks his middle finger up to the camera.

The Zimmers are an unlikely pop sensation - they were brought together by Tim Samuels, a BBC journalist who wanted to highlight the plight of millions of pensioners in the UK. He had he set out to make a documentary which explored how old people were treated in this country and came to the conclusion that they were getting a raw deal.

"So many are just dumped in care homes, stuck at home on their own, and generally marginalised. If you can judge a society by how well it treats its old people, we'd be in trouble," he said.

So Mr Samuels travelled throughout the country meeting what he called "marginalised old people", and asked them if they would be willing to have a go at making a single. He said it was a "faintly ridiculous idea", but they gave it a go and he thought that, if nothing else, "it would be a nice day out in London" for them.

The pleasant day out to the Abbey Road studios in north London, where the Beatles recorded many of their hits, turned out to be more than just a nice day of course. The Zimmers spent four hours in the studio and recorded a cover of "My Generation".

Not everybody reacted positively to the record - Dolores Murray, 68, said she was told by a young DJ that his station would not play the record because "old people smell of wee and they're rubbish".

However, they posted their video on the YouTube site and the hits began to flow in. In one scene, band members can be seen smashing up guitars, Pete Townshend-style.

Their video has now been watched by more than 2.3 million people, and about 100 million people in 50 countries have seen clips of the band on television. And more than 2 million people watched Mr Samuel's documentary, Power to the People, on BBC2 last Monday.

Will Daws, a producer on the programme, said: "Considering we weren't on any playlists, because we were not being young and trendy enough, I think this is an absolute triumph.

"Now we're in the charts DJs will have to play us and hopefully then we can break into the top 10."