Rain failed to dampen spirits of music fans arriving at Glastonbury on Thursday as the 900-acre festival site threatened to turn into a muddy quagmire. Campers hauling their bags and beers along the slippery thoroughfares were told to pitch tents on hills after some fields were flooded. More than half of the 170,000 ticket-holders for the sold-out event will have squelched their way to the site by tonight. The weather is predicted to remain changeable but certainly won\'t prevent music fans enjoying headline acts like U2, Coldplay and Beyonce, scheduled to perform on Friday, Saturday and Sunday. U2 pulled out of headlining last year\'s Glastonbury after singer Bono injured his back and fans are hoping the Irish quartet\'s long-awaited arrival on Friday will not be overshadowed by direct action tax protesters. Campaigners are planning to take a giant inflatable banner into the site with the slogan \"Bono Pay Up\" in lights. Art Uncut, a group with strong links to UK Uncut, hope the stunt will highlight \"the very real impact of U2\'s tax avoidance on hospitals and schools in Ireland\". Coldplay\'s Chris Martin completes a hat-trick as his band give a headline show for the third time in a decade on Saturday night. Martin credits Eavis and his invitation for the band\'s first headline set in 2002 as a pivotal moment for the band. Beyonce, who fell in love with the Somerset festival after watching husband Jay-Z perform three years ago, is believed to have cleared her diary to party in Pilton over three days. The American couple are expected to spend the whole weekend at the festival before she brings the curtain down on the Pyramid Stage on Sunday. Glastonbury, which sold out this year in four hours, takes a year off next June to rest the dairy farm\'s land.