PILTON, England (Reuters) -A hundred thousand people braved rain, cold and mud to see Irish rockers U2 at Glastonbury on Friday in their first appearance at the famous music festival.
The band had been due to play a headline slot on the main Pyramid stage a year ago, but lead singer Bono hurt his back putting their debut on hold.
There was a small protest as promised against U2's decision several years ago to switch its operations from Ireland to the Netherlands for tax purposes.
But it did little to distract the crowd, which sang along to some of the band's greatest hits including "Sunday, Bloody Sunday" to "Where the Streets Have No Name."
"I'm sorry to have called in sick last year," Bono told the crowd, his dark glasses covered in rain drops. "This is a very, very great occasion for us - we don't do this very often."
U2 is in the middle of a record-breaking world tour, but rarely performs at festivals and has never played Glastonbury.
A pressure group called Arts Uncut had aimed to embarrass Bono and the band by highlighting their tax status, and a large white balloon covered with the words "U Pay Tax 2?" was held above the crowd.
One man wore a T-shirt saying "Bono Pay Your Tax," but the gestures were barely noticed by the majority of onlookers.
Critics say Bono, a leading anti-poverty campaigner, should be prepared to pay full taxes in his homeland, particularly at a time of major financial difficulty.
Others argue it is the band's right to pay taxes legally wherever they wish, and that Bono works harder than most to highlight issues like poverty and disease.
"It's his money, he can do what he wants with it," said Freddie Cowan of British indie band The Vaccines who were performing at Glastonbury.
Earlier in the day, Radiohead was the "surprise" guest on the distant Park stage where it played songs from new album "King of Limbs" and other recent music.
Blues guitar legend B.B. King warmed up the Pyramid crowd on a cool, damp afternoon with classics including "Every Day I Have the Blues."
"I wanna shake my booty, but I'm a little old and a little cold," the 85-year-old called out to the crowd as he took a seat to perform with his band.
Most of the Glastonbury crowd that will peak at around 175,000 people, wore rubber rainboots to cope with fields of deep, cloying mud.
Bales of hay were dropped over the worst-affected areas to make walking easier, but persistent rain on Friday meant the mudbath returned.
The other headline acts are Coldplay on Saturday and Beyonce with the closing show on Sunday, following in the footsteps of her husband Jay-Z who won over the Glastonbury doubters with a rousing set in 2008.
Visitors have a bewildering choice of entertainment, with hundreds of bands performing across the 900-acre site.
Pop pundits have singled out Tinie Tempah, Plan B, Paul Simon, Primal Scream, Mumford & Sons, The Chemical Brothers, White Lies, Queens of the Stone Age, Cee Lo Green and Ke$ha as ones to watch.
Turned into a giant camping site most years, Britain's most famous music festival is now in its fifth decade.
Additional reporting by Cindy Martin; editing by Andrew Roche