Hard-partying celebrities Lily Allen and Pixie Geldof  were among the 200,000 revellers who descended on Glastonbury today for the start of Britain's biggest music festival.

The stars were spotted getting into the festival spirit with a drink in the backstage area today.

Lily Allen enjoyed a pint of local cider, while Pixie showed she was prepared for the notoriously rainy weather in a pair of welly boots.

Festival spirit: Party girl Lily Allen enjoys a pint of cider

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Lily Allen wears a funky pair of studded sunglasses

Alexa Chung was also seen backstage with Arctic Monkeys lead singer Alex Turner.

Pixie Geldof and Alexa Chung wore remarkably similar outfits - both sported nautical striped tops, black leather jackets and wellington boots.

However Pixie changed into a striking auburn wig and slashed T-shirt which revealed her black bra.

Alexa Chung and Alex Turner lead singer of the Arctic Monkeys backstage

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Larking around: Actress Jaime Winston with boyfriend Alfie Allen

Kelly Osbourne was also spotted in the festival's backstage area accompanied by her boyfriend model Luke Worrell.

Other celebrities include Kidadulthood actress Jaime Winston, journalist Andrew Marr and singer K T Tunstall.

After a day of sunshine to welcome a hundred thousand visitors to the Glastonbury site in Somerset, rain broke out last night spluttering proceedings to a start.

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Festival style: Pixie Geldof shows off a different look in an auburn wig (left) but keeps her hat on

Organiser Michael Eavis as always promised that drainage systems this year would be up to scratch.

But as music fans got under canvass for the first of three nights last night, it remained to be seen whether that pledge would, ahem, hold water..

With weather forecasters predicting moderate showers today and tomorrow and a dry Sunday, Glastonbury founder Eavis was confident there would be no repeat of last year’s chaotic scenes as hundreds of tents were submerged by mud and floods.

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Star-studded: Journalist Andrew Marr (left) and singer KT Tunstall

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Rhys Ifans puffs on a dummy cigarette (left) and Kate Nash performs on the main stage (right)

Opening the three-day event, Eavis shrugged off forecasts of more showers over the weekend, telling the crowds: 'We don't need welly boots this year.

'This is going to be a vintage Glastonbury. We have the best line-up we have ever had and the valley is full of really beautiful people.'

Torrential rain turned the site at Worthy Farm in Somerset into a mudbath last year, while in 2005 storms washed away dozens of tents.

It is the first time the festival has not sold out ahead of time in 15 years, according to media reports.

Pixie chats to Kelly Osbourne and her boyfriend Luke Worrell

However despite early fears over slow ticket sales, organisers of the three-day event are predicting a sell-out with 70,000 campers already pitching their tents at Worthy Farm in Somerset last night - and a further 110,000 arriving today.

Today, Tennessee garage rockers Kings of Leon headline the Pyramid Stage.

The outfit, made up of four Followills - brothers Caleb, Nathan, and Jared and their cousin Matthew - are expected to thrash out hits from their last three albums and forthcoming record Only By The Night.

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An aerial view of the festival site as thousands arrive for the three-day event

Scottish band The Fratellis, reggae veteran Jimmy Cliff and Irish singer Sinead O'Connor will also perform today.

Festival headliners also include  Britpop veterans The Verve and rapper Jay-Z, whose inclusion has upset rock and indie music fans.

Jay-Z, a Grammy Award-winner who is married to singer Beyonce, will play the main stage on Saturday.

Critics have blamed him for slow ticket sales. A weekend pass costs 155 pounds.

Noel Gallagher of Oasis said hip hop at Glastonbury was 'wrong', while traditionalists in Internet chatrooms said they would have preferred a band like Radiohead.

Organisers defended their choice, saying the festival that started in 1970 must move with the times.

Eavis said he would be at the front of the stage to welcome the rapper, wearing some 'lovely bling'.

'There will be diamonds and gold and everything,' he added.

Reggae veteran Jimmy Cliff headlines the Jazz World Stage - the 60-year-old being best known among mainstream audiences for songs like Sittin' in Limbo, You Can Get It If You Really Want It and Many Rivers to Cross.

Junkie rocker Pete Doherty will headline The Park stage for a solo acoustic set and is expected to play music from a forthcoming untitled solo album.

Elsewhere and throughout the day, music lovers can catch the soul-punk of The Gossip, fronted by larger than life Beth Ditto, emo rockers Panic At The Disco and indie popsters The Ting Tings, who recently scored a number one hit with their single That's Not My Name.

Troubled singer Amy Winehouse is due to play on Saturday after receiving treatment for a lung condition which her father said was caused by smoking crack cocaine.

It is rumoured she will join Jay-Z, Beyonce, Chris Martin and Rolling Stars guitrist Keith Richards to take part in the ultimate supergroup.

Elsewhere, poets, fire-eaters and mime artists will entertain the crowds.

Religious services will be held at a church tent, while pagans will meet up in the Healing Fields.