They have made a billion journeys to work bearable (for their wearers, at least) and been flourished by the rich, famous and powerful.

The super-slim music player with the shuffle function is simply the first indispensable style icon of the 21st century - and yesterday the 100millionth iPod was sold.

Apple sold its first iPod in October 2001 and since then has introduced almost a dozen new models, including five generations of iPod, two generations of iPod mini, two generations of iPod nano and two generations of iPod shuffle.

With it has come an unprecedented 'ecosystem' of more than 4,000 accessories ranging from cases to speaker systems.

The Design Museum in London features a 2001 version of the media player.

A staff member hailed the iPod as a 'design classic'.

To listen to all the 7,500 songs a 30GB iPod can hold non-stop would take 375 days.

And if all the iPods were stood end to end they would stretch roughly 10,000km - from London to New York and back again.

Among famous iPod users are the Queen, who owns a silver iPod. She was said to be impressed by how small and handy it is.

Chancellor Gordon Brown boasts: 'I've got an iPod and I know how to use it.'

Which is in contrast to well-known technophobe Tony Blair, who confesses that his daughter Kathryn has to download his music for him.

Also sporting the distinctive white headphones of the iPod are the Pope and US president George Bush, who revealed his list of tunes include Van Morrison's Brown Eyed Girl. A U2 special edition of the iPod was released in 2004 and last October Bono, the rock group's frontman, launched a charity Red version of 4GB iPod Nano.

It has not been all plain sailing. Scratched screens plagued the iPod nano for a time and when iPods were launched there were complaints that battery 'real-life' use was far less than the 14 hours claimed by Apple.