Lily Allen in foul-mouthed tirade at V Festival

Miss Allen, cancelled an American tour after immigration authorities revoked her visa over an alleged assault on a photographer, described the 43rd president as a "f****** c***".

The 22-year-old giggled her way through the 45-minute set at Weston Park, Staffordshire, and admitted "getting a little drunk" during her performance.

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Earlier, thousands of music fans braved the rain and wind for the opening of the festival at Weston Park and Hylands Park in Chelmsford, Essex.

Dressed head to toe in brightly-coloured waterproofs, up to 83,000 festivalgoers poured into the main arena at Weston Park to see the likes of The Goo Goo Dolls, KT Tunstall and Sophie Ellis-Bextor on the first day of the two-day festival.

In what organisers have described as the best ever V event, revellers jumped for joy as their favourite bands took to the stage.

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Screams of delight could be heard as the popular soloist James Morrison entered the stage to sing some of his best known songs, including It's A Wonderful World and You Give Me Something.

Many caked in mud but with smiles on their faces danced away to Scottish rock veterans The Proclaimers as they belted out their classic hit I'm Gonna Be (500 miles).

For some, camping in the rain and mud had become too much and they packed up their tents at first light today ready to make an impromptu exit after the festival this evening.

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Adam Longley, 27, and his four friends had decided to return to Liverpool this evening. He said: "We were planning to stay and camp tonight but it's too wet and too cold so we thought we'd enjoy the festival today and head back once it's finished.

"It's been a really good weekend despite the weather and we've seen some amazing bands do some really good sets. We particularly enjoyed yesterday's headliners The Killers and we're looking forward to seeing the Foo Fighters tonight."

Yet the wet weather did by no means deter all the fans. Festival goer Sarah Hardy, 22, from Derby, said: "So far it's been absolutely brilliant. The weather has been terrible but I go to these festivals all the time so I've come to expect it. In fact, the rain adds to the experience."

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Co-ordinator of the festival, Dawn Woodhouse, said the weather hadn't put people off and described it as the best ever.

She said: "A lot of people have packed up their cars ready to go back tonight because of the weather but we've still found that everyone has had a really good time.

"The same thing happened last year with the weather and people still had a good time. This year we had a lot of contingencies in place to help the concert run smoothly, such as a park and ride from Telford."

Headliners tonight are the Foo Fighters and Snow Patrol.

Also performing tonight is female artist Pink, hip-hop artist Kanye West, the Kooks and the Fray.

Police also made at least 67 arrests at the Midlands' music festival. Of the 67 arrests, 32 were for possession of drugs and nine were for possession with intent to supply.

Seventeen people were arrested on suspicion of theft and three were held over assaults.

Arrests were also made for a public order offence, criminal damage, deception, a positive breath test and for possession of an offensive weapon.