Glastonbury Festival, Worthy Farm, Pilton, Somerset

"It's not often you hear an Irishman singing "Jerusalem", Bono notes.

It's a particularly ragged, even rotten attempt. But it's symptomatic of his wish to connect with Glastonbury, a festival whose specialness partly comes from association with ancient Albion. The controversy ahead of his band U2's headlining appearance on Friday night, stoked up by protesters against Bono's alleged use of tax havens, feels irrelevant as he plays. A version of "One" resonates with devotion, spirituality and suffering.

Bono slips in a fragment of Primal Scream's "Movin' On Up" into "I Still Haven't Found What I'm Looking For", too. An acoustic run at "Stay (Faraway So Close)", though, is flaccid. And, for all his songs' over-reaching grasps at wonder, Bono remains an uncharismatic performer, a great rock star by profession, not nature.

"Hello, we're called Radiohead," Thom Yorke announces earlier, for once with good reason. Their surprise slot on the obscure Park Stage leaves them almost invisible to much of a huge crowd, drawn by last minute rumours. Any thought of a repeat of their famous Glastonbury triumph in the days of OK Computer are quickly put away. Instead they play a low-key set largely drawn from their new album, King of Limbs. This suits a band who have turned their career down and inwards. They're more of a modern English jazz and funk outfit than stadium rockers now.

The relaxed place they've arrived at is shown in Yorke's voice. He once quivered with irritatingly affected angst. But on "Separator" he's an easygoing soul crooner, an Oxford Al Green. "Give Up The Ghost", begun as almost a capella two-part harmony, with just a soft pulse-beat of drums, is a humble prayer, the loveliest thing I've heard here so far. It's a surprise only Morrissey, whose simultaneous set on the main Pyramid Stage draws a noticeably thinned crowd, could begrudge.

Wu-Tang Clan are Friday's first real success. The old fuss about Jay-Z's headlining slot seems even more inexplicable as the crowd at the Pyramid Stage make the "W" sign for Staten Island's 1990s hip-hop rulers. They've fallen from their early heights, but this surprisingly happy, slick show compensates with understated funk, martial arts movie samples and eccentric clothing choices: Method Man greets Glastonbury in a white dressing gown. UK indie flavours of the moment the Vaccines, at the Other Stage at the same time, can't really compete.

BB King follows them. His supposed farewell European tour, as diabetes left him barely able to stand, was a few years back, and he seems set to continue to the end. It's true he can play anything on his legendary guitar Lucille and get a cheer. The first few jagged notes from this graceful man raise my spirits anyway.

As I approach Kentucky's Cage The Elephant, they're finishing a song which sounds like The Band playing "Love Will Tear Us Apart". Singer Matthew Shultz is soon channelling Jim Morrison's shaman moves, pulling his shirt round him like a straitjacket. His band sometimes roar in the style of Nirvana, but this spirited and second-hand concoction doesn't quite convince.