While Glastonbury addresses a middle-class, middle-aged crisis, you only have to join the queues of Prommers 125 miles away to be part of a truly populist music festival. There is nothing starchy about the broad crowd who pay £5 to stand through a Prom concert. Snaking down the steps outside the Albert Hall is a friendly gaggle of students, teens, OAPs, kids and everyone in between. And there’s a Times reader, Leslie McLeish from Aberdeen, eagerly awaiting today’s Proms voucher ( below), which he’ll use to get into tonight’s concert for free.

This is where a night at the Proms begins, in chatter and anticipation. A posse of 16-year-olds talks excitedly about hearing the Striggio Mass, rediscovered after 300 years. Others do crosswords and tuck into impromptu dinners. A champagne cork pops for a birthday celebration. Friendships form . . . love blossoms. Something of a Proms legend, Shelagh Cohen met her husband, Jules, in the queue 33 years ago. “We shared the score of Walton One,” she explains, breathlessly.

The great mystery of the Proms is its audience; people who don’t regularly attend other classical concerts come to the Proms. Why? For a start, the music; where else can you hear such a varied programme, played by world-class orchestras, back to back over two months? In the first week alone you could have experienced music across three centuries, by 31 composers, played by eight different orchestras.

Emmet O’Donnell, 25, is attending his second Prom in two nights. A sound engineer, he’s a fan of “experimental noise music and anything a bit left of field”. You won’t find O’Donnell rocking up to the Queen Elizabeth Hall. Classical concerts there are “too safe. I like things a bit more extreme. The Ives Fourth Symphony [playing that night in Prom 5] is fairly intense.”

Intense is the word. And all of this art is wonderfully accessible. For £5 – zilch if you present the Times voucher – you can show up and listen. Prommers do this standing up, lying down and sitting. At times the Arena – the main floor of the Hall – resembles The Weather Project at Tate Modern, where punters stretched out and gazed at Olafur Eliasson’s mirrored ceiling. As one proud Prommer observes: “People are here for the music, not for show.”

In many ways, the Proms are as close to a pop gig as classical music will ever get; hundreds of sweaty bodies jostling to hear a band. First-time Prommer Elizabeth Roche, 16, goes regularly to recitals at the Wigmore Hall but, she says, “I want to be able to listen to beautiful music with a huge number of people.”

For others, the Proms are a ritual. Season-ticket holders – those with a ticket to every concert – attend upwards of 50 Proms. There used to be white lines drawn on the Arena floor separating season-ticket holders from day Prommers. The lines have gone, but the rules still apply, informally. Day Prommers stand on the right, facing the conductor; season-ticket holders occupy front left. Love them or laugh at them, the season-ticket hardcore lend the Proms many of its most famous quirks, including the “shouts” from Arena to Gallery. “Heave!” they yell, as the stagehands move a piano. “Ho!” the Gallery responds.

I wonder if Lee McLernon and his fellow Arena “shouters” have ever ventured upstairs. “A trip to the dark side?” quips one. The dark side – the wide Gallery that runs around the top of the Hall – is more like an elegant picnic spot. It’s as if Hyde Park has crossed the road and moved indoors. “It is more relaxed up here,” says Hazel Morgan, a Gallery-goer from Essex, who rents digs in London for the Proms. “It’s a different mindset down there,” she adds, jerking her head towards the Arena. “Those people at the front always get seen on TV. They like to feel they’re carrying on the ‘tradition’ of the Promenaders.”

I detect a whiff of envy. But perhaps she simply enjoys looking down on the Arena ants below. One certainly gets a dizzying sense of the Albert Hall’s scale from up there. And the acoustics are different; the voices of the Tallis Scholars, performing Striggio, float up with crystal clarity.

But even the keenest Prommer struggles to articulate exactly what it is that draws them to this great summer tradition. “The Proms drag me in,” says one man, while Jon Jacob, a Facebook Proms blogger no less, explains: “I feel as though the Proms are all for me, there for the taking if I wish.”

— Five hundred Arena and Gallery tickets are available for every concert, cost £5. BBC Proms, Albert Hall, SW7 (020-7589 8212). www.bbc.co.uk/proms/2007

Explore Music

• Festivals

• CD Reviews

• Live Reviews

• Classical

Editor's choice

• U2 at Nou Camp Stadium, Barcelona
• The 50 Best Movie Villains
• The 15 golden rules of theatre etiquette