Marcus Thompson wanted to make a film of the Jacobean tragedy 'The Changeling'. He wanted stars. The only problem: no money.

Lucinda, the PA on The Changeling, the first movie ever to have received it's premiere at the Glastonbury Festival - on Saturday - sits in the canteen at Pinewood Studios and explains the catalogue of incredible coincidences that have blessed this strange production since Day One.

"Do you realise," she says, "how weird, how appropriate this all is. "It's the 25th anniversary of Glastonbury, the movie finished shooting on June 25th last year, the first public screening is being shown on the morning of the 25th, it's 25 years since Jimmy Hendrix died, and I'll be 25 this year."

Marcus Thompson, the film's director, hastens to add that this whole 25 thing wasn't the actual reason for choosing Glastonbury - it was just an added bonus.

"But you've got to admit," he says, "it's all pretty extraordinary."

The truth behind Saturday's curious premiere - in a huge, slightly damp field at 2.00am - is, in fact, somewhat more prosaic. They tried to get the movie ready for Cannes but failed, and this seemed like a good idea.

The Changeling - Middleton's Jacobean tragedy, re-worked in a modern- day Alicante with a Jimi Hendrix soundtack - has been six arduous years in the making, and it still wasn't finished last week, even though the Glastonbury clock was ticking away at an alarming pace. A technician from the Pinewood dubbing studio asked Thompson what time, exactly, on Saturday the film was due to be screened.

"2.00am," replied Thompson.

"Well," said the technician, "that's not Saturday, is it? That's Sunday. That gives us a bit of time to play with."

"And that," explains Thompson to me now "is how scary this all is."

In an hour, we hope to see for the very first time a dubbed and digitally mastered copy of Reel One. Thompson is completely broke - has been for six years - so we're consequently compelled to slip furtively into Pinewood's main screening room during the coffee break for the rushes of Tom Cruise's Mission Impossible.

"Have you got a spare 10 minutes?" Thompson asks the projectionist, sheepishly. "It's just that we haven't got any ... um..."

"Money?" replies the projectionist wearily.

"Yes," says Thompson, nervously. "But, you know, it's the most fascinating thing. We've put the soundtrack on the sprocket holes, and it really is a fascinating process."

"Oh," tuts the projectionist, "OK, then."

Over pre-screening tea in the canteen ("I'm afraid that I told them you'd pay," admits Thompson, blushing), he recounts the bizarre tale of how a pounds 1.6 million film can be made for absolutely nothing.

"British Screen said we were too ambitious, and the BFI said we were too commercial. We've been rejected by absolutely every official body in Britain." Thompson grins proudly. "So everyone deferred payment. All the crew, Ian Dury, Billy Connolly, even Jimi Hendrix's estate - and they once charged someone $350,000 for the use of the line 'Excuse me while I kiss the sky'. The guy who heads the Hendrix estate said to us: 'If the film is as weird as you say, then maybe we can do business.' So we showed him a rough cut and he said: "Well it's as weird as you say'. Where's your car parked?"

"Um," I reply. "Over there."

"That's were we built the interior of the castle," says Thompson. "Car Park 4. Every night for five weeks. Pinewood let us have it for pounds 100 a week." He pauses, and shakes his head. "Bless them."

On the way to the car park, I get chatting to the studio's security guard, who remembers with some pleasure, the nights when a bunch of "new-age traveller types" would descend upon Pinewood at dusk "always asking to use the toilet and borrow cups of tea." He pauses and smiles. "Of course, I didn't mind because the girls were all good-looking."

"The car park looks like a car park again now although it still gives me a hell of a buzz," says Lucinda the PA. "See where that fiesta is parked? Well, that was the master bedroom." This is Marcus Thompson's first "proper" film, although he has dabbled in pop-videos ("for lots of bands you've never heard of like Ocean Colour Scene") and was a film editor at Granada for years. The leading actress is another unknown, ex-Michael Clarke dancer Amanda Ray-King. Her parents designed the sets, and put the money they'd saved to help her buy a flat into the film. There's no doubt that Thompson's overwhelming, obsessive, unfailing, chain-smoking enthusiasm was the key factor in the successful completion of this ostensibly impossible task. "Me and Amanda spent months in a camper van, driving through Europe, meeting all these big-wigs," he says. "We'd have all these high-powered meetings in cocktail bars with Spanish royalty, and then go off to sleep in a car park."

It's time now to see Reel One, and the anxiety in Thompson's face is almost heartbreaking. He, Amanda and I take our seats in the screening room - seats still warm from Tom Cruise's multi-million dollar rushes screenings - and the lights darken.

Everything begins fine. The opening shot is of Alicante at twilight, fireworks blazing lavishly in the port, and then we cut to Amanda walking through a church. She opens her mouth to utter her first lines. Her mouth moves, but the words don't come out. Then she closes her mouth, and speaks.

"Fuck," says Thompson, quietly.

Ten minutes later, the lights come up. "It's the analogue plop," says Thompson.

"Oh God," says Amanda, ashen. "The analogue plop."

"What's an analogue plop?" I ask.

"I'll show you," says Thompson, and draws a lengthy - and entirely incomprehensible - diagram on a paper napkin.

"It's a big problem," says Thompson, his voice trailing off - to silence - for the first time in our three-hour conversation. "Look, um, you'd better..."

"I'll go," I say.

"It'll be fine," says Thompson. "Just leave it to ... the production's blessed ... it'll be fine.

And I leave Thompson, looking ashen, nervous, heading towards the telephone.