By Olivia Hunt
BBC News at the Underage Festival, London
It was a perfect summer day as 5,000 teenagers descended on Victoria Park in London for eight hours of music and partying at the Underage Festival - where anyone aged 19 or over was banned.
No parents or guardians were allowed to attend the festival
The event had a fantastic list of up-and-coming young bands, including The Pigeon Detectives, The Mystery Jets and Jack Penate.
It was the brainchild of 15-year-old schoolboy Sam Killcoyne, who started the Underage Club a year ago.
And it took pride in being the world's first credible music festival for those aged 14 to 18.
Tickets were just £20, making them far more affordable to young people than Glastonbury or Reading.
A strict no-adult policy was enforced and all teenagers had to show ID. Even the reporters had to be under 18.
Teenagers could drop their parents off in the "adult" creche - surely a first - and collect them post-festival.
Thirty acts were on the bill, including violinist Patrick Wolf (right)
The long queues to get into the festival meant that even people who had pre-purchased tickets had to wait for more than an hour, missing some of the acts.
There were four stages - hosted by Radio One, MySpace and Converse/Artrocker, plus a Converse New Music Stage.
Although the bands were predominantly indie and rock, other acts including Lethal Bizzle, Johnny Flynn and Kitty, Daisy and Lewis resulted in a mix of music to suit all tastes.
Each band played a set of between 20 and 30 minutes.
Among the highlights of the day were The Pigeon Detectives.
They have had a fantastic year, playing at Glastonbury and having their album Wait for Me reaching number three in the charts.
The crowd sang along to every song and went wild to I'm Not Sorry and their new single Take Her Back.
"The Pigeon Detectives were amazing," raved one fan.
Leeds-based group The Pigeon Detectives thrilled festival crowds
Electric anticipation awaited Lethal Bizzle, and chants of "Bizzle! Bizzle!" preceded the rapper's set, which was almost as energetic as the crowd's reaction to it.
He kept asking for the music to be turned up. When he sang Jump Around, the fans loved it and no-one could jump high enough.
"How do you follow on from that," asked Laura Marling, who went on stage after him.
Obviously nervous, the 17-year-old folk singer-songwriter managed to mellow out the crowd with her clear pure voice and modern lyrics.
Over in the Converse circus tent, I Was a Cub Scout played a shorter-than-planned set owing to a technical hitch, but the crowd loved them.
The oldest member of indie band Cajun Dance Party is 17, and they are set to be massive.
Their new single, Amylase, went down really well with the crowd. They finished the set with the title track of their album The Next Untouchable.
The atmosphere was akin to that of a village fete, our reporter said
The Mystery Jets attracted a massive crowd, a "fantastic performance", said Dan, 14.
Jack Penate was playing the Radio One stage, and he was "awesome", according to 16-year-old Sarah and her friends.
Elsewhere, Mumm-Ra - voted one of the NME's best new bands of 2007 - played to an enthusiastic crowd.
And Patrick Wolf, dressed in a toga, closed the Converse tent, jumping around while playing his violin and looking like something out of A Midsummer Night's Dream.
He told the crowd that he would have stripped but the organisers wouldn't let him. This resulted in uproar.
Some teenagers tried to smuggle in alcohol but security was tight and contraband confiscated, although inevitably some made it through.
But generally the day was all about the music and was largely free of alcohol and drugs.
Many groups of teenagers chose to sit down, enjoying the sun and the music, whilst others went right into the centre and crowd-surfed.
Corporate sponsors included BBC Radio 1, MySpace and Converse
It was a far cry from the awkward and tacky underage club nights organised by 40-year-olds.
The venue proved excellent, with plenty of food stalls selling everything from burgers and chips to organic sandwiches and noodles, all quite reasonably priced.
Its fete-like atmosphere created an intimacy lacking at many music festivals.
This was a festival for the young and effortlessly cool. It was a true celebration of youth and its talent.