Having a choice between the bar and a band is no longer enough for some festival-goers. Events increasingly distinguish themselves with themes, some merely encouraging fancy dress, others transforming their whole site into a temporary escapist fantasy of giant board games, Agatha Christie whodunits or medieval romance, in which the music can sometimes seem incidental.
The trend began with the first Bestival on the Isle of Wight, in 2004. "We were head-scratching in the pub, trying to think of how to make it unique," organiser Rob da Bank remembers. "We'd already flirted with fancy dress in the clubs we'd been doing, and announced it for the first one. We thought maybe a couple of hundred would participate, but half of the 4,000 at the first festival did. The second year it was 10,000, and now it's a core thing about Bestival.
"The idea was to add colour to the show, and to make it more inclusive. Rather than just watching some bands and having some beer and burgers, we want people to be the show themselves. People get in their costumes, and stay in them all weekend sometimes. It's very much a kind of escapism."
Bank sees the experience at his festival as more than a bit of Saturday night, school disco-style dressing up. While its crowds get to act like superheroes, putting on secret identities for the weekend, Bestival has crossed the traditional festival with the annual, painstaking preparations more familiar at carnivals such as Notting Hill. "People spend months making costumes," Bank explains. "They have meetings where they go round to each other's houses, planning and designing, it's a big enterprise. That's why we keep the themes really open now. The last two have been space and fantasy, and this year it's pop stars, rock stars and divas. We want people to be free to go to town, and use their imaginations."
More mainstream festivals have incorporated fancy dress days. This year, Scotland's massive T in the Park has just the sort of cheerfully retro 1980s theme that Bank distances himself from. At the other extreme, the new Wilderness festival (on the Oxfordshire site of the old Cornbury Festival) is mixing refined bands such as Antony and the Johnsons with lectures on philosophy, nanotechnology and the future. At least one Oxford don is on the bill. This educative atmosphere can also be found in Einstein's Garden, a child-friendly zone of nature and science at the Green Man Festival. The BoomTown Fair will turn its rustic site into a city, complete with town centre and ghetto. Festivalgoers are encouraged to people it as doctors, nurses, butchers, postmen or whatever civic identity takes their fancy.
Standon Calling creates a similarly immersive experience. Its 16th-century Hertfordshire country house setting was ideal for last year's crime theme, when village "shops" were built with interactive theatrical experiences inside. The manor's Lord Trenchard could be seen wandering around as Poirot. "A heritage arts company designs a theatrical side which is all around you from when you arrive," says organiser Graham MacVoy, "in signs, games, hunts and shows. Every year, the whole festival gets designed once the theme's been decided, from the marketing to the interactive theatre to the acts, to an extent. The theme's Gods and Monsters this year, and Spiritualized are headlining."
The idea is for the festival to be its own world for the weekend, not merely a holding pen in a field where acts are wheeled on-stage. "It's there for you to join into if you want to," says MacVoy. "The more you get involved, the deeper you immerse yourself. With last year's village shops, you had to go in and investigate what was there. Don't get me wrong, some people still just come and get trashed. But that doesn't have to be the only thing you do. You can spend your afternoons wandering, or have a few hours by the swimming pool, relaxing."
Gloucestershire's small Winterwell festival, now in its fifth year, has built its reputation on imaginatively realised themes throughout its Cotswolds valley site. "The first year was based around the idea of fairy tales," says founder Josh Ford, "because the valley feels like a fairy-tale setting, and we wanted to illustrate the magic and pleasure we get from it. The effort people made with fancy-dress was incredible, so we carried on.
The theme this year is Battle of the Board Games. A team of 30 artists are theming the whole site. We plan to have a giant game of snakes and ladders on the side of a hill. People will be able to physically jump from square to square, and we have a giant scrabble competition on a 24-foot wide scrabble board."
This literal playfulness illustrates the return to the more child-like, open-minded state that themed festivals often seem to aim at. "It's about creating a great party for three days," Ford agrees, "and there's nothing like fancy dress to take down people's barriers and inhibitions."
Deer Shed's Sky At Night theme is named after and based around the latest album by their headline act, I Am Kloot. Oliver Jones, co-founder of the North Yorkshire festival, says: "I was thinking how do we support their performance? And they're all mad into astronomy. It's the only festival they're headlining, and so playing under the stars. And because we're family-oriented, this is a thing that kids are into. We're doing all we can to support the theme, with stargazing, and a cosmodome – a blow-up planetarium that we're getting from York University.
"We're hoping to send a helium balloon into the atmosphere, with a digital camera and mobile phone to report back. A theme really helps when you're trying to programme because it gives you focus."
Deer Shed's family-oriented approach can also be seen at Bestival's more child-friendly offspring Camp Bestival, where a massive Mad Hatter's Tea Party was once held. Back at Standon Calling, they are also centring the weekend on their headliner. "Everything in the theme is building towards Spiritualized on Saturday night," says MacVoy. "People will learn how to do pagan ritualistic drumming at workshops, and then eventually the whole site goes dark and silent, and we have this big obelisk at the centre of the arena which everybody focuses on. Then there'll be a very special moment, leading up to Spiritualized."
The biggest shift at themed festivals, though, is that the music is sometimes incidental. This makes smaller events such as Winterwell, which can't afford big acts, suddenly viable. "People don't come specifically for the music," Josh Ford agrees. "They come because they know they'll have a good time, with a community of like-minded people."
Winterwell, 17-19 June, www.winterwell.co.uk
Deer Shed Festival, 22-24 July, www.deershedfestival.com
Standon Calling, 12-14 August, www.standon-calling.com
Bestival, 8-11 September, www.bestival.net