Wellies at the ready as Glastonbury Festival turns 40

Over 170,000 people are expected to attend Britain's famous Glastonbury festival this weekend as the world's largest open-air music and performing arts event celebrates its 40th anniversary.

Revellers are packing their wellies and wet-wipes as they prepare to descend on the festival in Somerset, southwest England, which opens its doors on Wednesday, two days before the music begins.

It may be approaching middle age, but the festival is still renowned for attracting the planet's most revered musicians as well as encouraging more left-field and underground performance artists.

Organiser Michael Eavis, 74, received a blow when Irish rock megastars U2, who were due to headline the main Pyramid Stage on Friday, pulled out after frontman Bono injured his back.

Stepping into the breach are Gorillaz, the hip-hop influenced side-project of Blur singer Damon Albarn.

Other heavyweights performing this year are US soul-pioneer Stevie Wonder, rapper Snoop Dogg, Latino superstar Shakira, American quartet Vampire Weekend, country icon Willie Nelson and rockers Muse, who headline on Saturday.

It is not just mainstream music that is represented, with 45 official stages offering performances from 700 artists as diverse as Australian polymath Rolf Harris, Nigerian singer Femi Kuti and reggae veterans Toots and the Maytals.

For the rest of the year Eavis has his hands full running his Pilton dairy farm, but for one week the cows are moved away and his land becomes a stage for the world's biggest party.

Eavis first organised the festival in 1970, the day after Jimi Hendrix died, and fans who came to see acts including Marc Bolan and Al Stewart paid one pound each for entry and received free milk from the farm.

The festival was held intermittently in the 1970s and it wasn't until the 1990s that it really began to acquire its current status.

A successful headline spot can catapult bands to superstardom and legendary performances from Radiohead in 1997, Coldplay in 2002 and Muse in 2004 elevated these bands to their current heights.

There was controversy in 2008 when rapper Jay-Z was given a headline slot, but the doubts were dispelled after he delivered one of the most memorable sets ever.

The festival has had its darker moments; 235 people were arrested in 1990 after travellers started fighting with police, and the start of last year's event was marred by the news of Michael Jackson's death.

Integral to the festival's development was the late Arabella Churchill, granddaughter of Winston Churchill, who set up and then ran the Theatre and Circus fields.

As a result, the festival developed a diverse reputation and the 900-acre (360-hectare) site now encompasses various thematic areas.

One of these zones is Shangri-La, in which artists set out to create "a futuristic citadel, nestled next to an overpopulated slum riddled with filth of all kinds."

Shangri-La creative director Deborah Armstrong explained to AFP: "We've got artists on all levels, from the well-renowned, Art Council funded, to festival-goers. They're all tying into this narrative.

"Michael (Eavis) is the only person that's investing in this subculture and I think this is what is keeping Glastonbury unique," she added.

Much of Glastonbury's mystique is tied up with its links to ancient mythology.

King Arthur is believed to be buried at the foot of the nearby Tor while rumour has it that a young Jesus once visited the area with Joseph of Arimathea, inspiring William Blake's famous poem, "Jerusalem."

It is equally known for its unpredictable weather and knee-deep mud, 300 tents were washed away in 2005, and visitors to the festival will be keeping an eagle-eye on the local forecast.

In true British stiff-upper lip fashion, festival-goers tend to revel in their resilience, and whatever the weather, they will do their best to prove that life really does begin at 40.