THE STORY of Hay-on-Wye is more than a little unbelievable. Four decades ago, a bookseller decided that the sleepy little rural town was the ideal place not just for one bookshop, but for a whole series of them.

His idea was a success, and so in 1976 the booksellers of the town got together and decided they could promote their businesses by holding a small literary festival.

In 2004, 40 years after it all began, the Hay Festival is Britain's most prestigious literary gathering, described by Bill Clinton in his keynote speech last year as a "Woodstock for the brain".

This year's festival has the usual star-studded guest list, beginning tonight with a live appearance by Sir Bob Geldof. Saturday offers breakfast with Guardian sketchwriter Simon Hoggart, a comedy writing workshop from Birds of a Feather creators Laurence Marks and Maurice Gran, Tony Parsons discussing his new novel, mountaineer Joe Simpson talking about the story that became the award-winning film Touching the Void, and panels featuring James Kelman, Iain Sinclair, Zadie Smith, Hugh Fearnley Whittingstall, Ken Loach and other luminaries.

And from Gwent, Manic Street Preacher James Dean Bradfield will be talking to his theatrical collaborator Patrick Jones about their work together and political beliefs.

On Sunday, big names include Clive James talking about his search for the magic sentence, Robin Cook talking about his time in Blair's war cabinet, Python Terry Jones discoursing on medieval history, and the legendary American novelist John Updike on his life and work.

Monday sees John Pilger discussing the War on Terror, Magnum photographer David Hurn talking about his portraits and photojournals of Wales, and a live performance from Benjamin Zephaniah.

And there are plenty more visitors until the following Sunday, including Patrick Marber, Colin Dexter, Peter Blake, Julian Barnes, Mark Thomas, Bamber Gascoigne, Kate Adie, and more. For more information visit www.hayfestival.co.uk.