Rock superstars Metallica made a surprise appearance at the Download music festival in Derbyshire on Sunday.
Metallica: Long queues to see the band
The US band were not part of the published bill, but appeared unannounced on the festival's second stage on Sunday afternoon.
Just 8,000 people at the 40,000 at the festival were able to see the show by the veteran band, with many more queueing to catch a gimpse of them.
"They went down a storm, it was the best thing that could have happened to the festival," Steve Guest, a spokesman for promoter Clear Channel, told BBC News Online.
"News got around by word of mouth, and the overspill from the Scuzz stage was amazing.
"Everyone was enjoying it, we've had kids of six and seven holding onto their dads' shoulders giving out rock signs."
Festival-goers at its Donington Park site enjoyed hot sunshine on Saturday, and while the sky clouded over on Sunday, "everyone's still having a great time," Mr Guest said.
The event had been hit by the withdrawal of US band Limp Bizkit last month, and organisers had to deny reports that Metallica were appearing because of contractual reasons.
Metallica are headlining the Reading and Leeds festivals in August, which are promoted by Clear Channel's rival Mean Fiddler.
It is usual for bands at the top of a festival's bill to have it written into their contracts that they can only be associated with that event - so appearances at any other shows would have to be kept secret.
Download festival-goers are allowed to obtain free performances by bands appearing at the event from the internet.
Ironically, Metallica blocked 300,000 of their fans from using unlicensed download service Napster in 2000 because of copyright concerns.
Marilyn Manson was another Download star
Other acts appearing across the weekend included Marilyn Manson, Iron Maiden, Deftones, Evanesence, 80s Matchbox B-Line Disaster and Instruction.
NOFX, Less Than Jake, Zwan and Audioslave closed the show on Sunday night.