By Ian Youngs
Music reporter, BBC News, at the Glastonbury Festival
Harris was armed with his famous "wobble board"
The Glastonbury Festival has kicked off in earnest with veteran singer and artist Rolf Harris taking to the main Pyramid stage.
A huge crowd gathered in the sunny weather to see the 80-year-old sing a selection of his songs.
Willie Nelson, Snoop Dogg and Dizzee Rascal are all on Friday's line-up.
Damon Albarn's cartoon pop crusaders Gorillaz have stepped in to replace U2 as headliners, and are due to be joined by Lou Reed, Mark E Smith and Mos Def.
The forecast for the weekend is for sun, with temperatures reaching 28C.
More than 1,180 people have already been treated by medical staff, mostly for heat-related problems such as sunstroke and dehydration.
Emily Eavis on all things Glastonbury
But the fine weather has been welcomed by many fans, who are more used to experiencing Glastonbury in the mud rather than the sun. It has rained at every festival since 2002.
"The buzz is great," says Lee Boyce, 23, from Southend-on-Sea. "This is our first festival ever. Because it's the 40th [anniversary] it feels like something special."
Laura Tonks, 24, from Stoke-on-Trent, is also at her first Glastonbury. "It's one of those things where, if you like live music, you have to do it," she said.
Fans have been arriving at the site since Tuesday
"It's one of those lifetime achievement things. It's going to be epic."
Her friend Jessica Leese, 23, said she was keen to see Gorillaz, who replaced U2 after Bono injured his back.
"I wouldn't have made the special effort to see U2 but when I heard Gorillaz were playing I was really pleased," she said.
Another fan, Doug D'Souza, 31, from London, said: "I was happy that U2 pulled out. I think Gorillaz are perfect for the occasion because they are the most modern, contemporary band."
Gorillaz are also expected to be joined by guests including Mos Def, De La Soul, Pharcyde, The Syrian National Orchestra and Gruff Rhys from Super Furry Animals.
"We've got about 50 or 60 people at one point on stage," Albarn told BBC Radio 4's Front Row.
Rumours about possible festival surprises include members of U2 joining Gorillaz, Kylie Minogue singing with Scissor Sisters and Radiohead's Thom Yorke performing on The Park stage.
Boy George took to the stage on Thursday night
Other acts on the bill on Friday include Florence and the Machine, Groove Armada, Femi Kuti, The xx, Fatboy Slim and Mumford & Sons.
Some smaller stages opened on Thursday, hosting artists from Vanilla Ice and Boy George to up-and-coming bands Local Natives and Chapel Club.
The festival is celebrating the 40th anniversary of the first event, when 1,000 hippies turned up to watch Marc Bolan at Michael Eavis' dairy farm in Pilton, Somerset.
Billy Bragg led a chorus of happy birthday to Mr Eavis and his daughter Emily backstage on Thursday.
Crime has also dropped off from last year's festival, with 163 reported crimes so far and 47 arrests, mainly for drug offences.