Anvil: the real-life Spinal Tap

I was showing my two new friends around Westminster Abbey. It was 1982, and Robb Reiner and Steve "Lips" Kudlow were the founder members of Anvil, a Canadian rock band. They were in their mid-twenties and looked like Hell's Angels, but they were amiable, charming and great company. I was a 15-year-old public schoolboy and I revered them.

When we reached Poets' Corner, I said, "This, gentlemen, is the tomb of Charles Dickens."

"Whoa, dude, that's totally heavy," said Lips.

"Awesome," agreed Robb. "Totally." He looked thoughtful. "Wasn't he the original vocalist in Judas Priest?" I couldn't be sure he was joking.

Back then, Anvil were the Next Big Thing. Robb and Lips, childhood friends, had put together the four-piece outfit in 1978. They were pioneering a new form of very fast, very raucous heavy metal, driven by Lips's frenzied guitar playing and Robb's drumming. In April 1982, Lips had appeared on the cover of Sounds dressed head to toe in black leather, brandishing a chainsaw and clenching a sex aid between his teeth. I was a fan before I'd heard a note. I rushed out to buy the band's ground-breaking second album, Metal on Metal, which Kerrang! had declared a work of genius, awarding it the coveted five-"K" rating.

When I heard Anvil had a gig at the Marquee, I knew I had to be there. The band blew the roof off the venue. Their songs were brilliant. "Butter-Bust Jerky" detailed an exotic practice involving dairy produce and an ample lady. "Show Me Your Tits" was, Lips insisted, a political song celebrating women's freedom of expression.

After the show, I tricked my way into the band's dressing room, where I introduced myself to Lips and Robb as Anvil's number one fan in England. Robb told me the band had never been to London before. "You wouldn't mind showing us around, would you, kid?" Lips asked.

The next day, I became Anvil's tour guide. I later brought them back to my house, where my shocked mother, a concert pianist, gave them tea. "I want them out of this house in 20 minutes," she hissed. I couldn't have been more thrilled. By the end of the day, they had invited me to come on the road with them. "We're going to call you 'Teabag'," added Robb. "That's your new Anvil name."

I was part of the Anvil family now. In the summer, I told my mother I was going to visit my father, a diplomat, in New York and I joined Anvil on a tour of hockey arenas. I sold T-shirts, humped gear and helped Robb set up his kit. There was a great deal of "partying with chicks". During one soundcheck, one of the band had sex with a groupie in the vehicle used to keep the ice clean. I was having the time of my life. When my mother found out that I wasn't staying with my father, she sent him to rescue me. He turned up after the band had finished playing, in his suit and cravat; they were in bondage harnesses but on best behaviour, and Dad decided they were fit and proper persons to be in charge of his son.

Anvil and I grew apart. I began to play in a band I formed with a schoolmate, Gavin Rossdale, but left, convinced we were going nowhere. The band changed its name to Bush, and, a year and a half after I'd left, I was at the LA Forum, surrounded by 30,000 girls screaming out lyrics to songs I'd played in a rehearsal studio only months before.

Inspired by Withnail and I, I chose a career in movies. A script I co-wrote was made into The Big Tease by Warner Brothers. Warner next asked me if I'd consider adapting a children's book about a wizard called Harry Potter. I turned them down, citing "its complete lack of commerciality". By 2005, I had finished working with Steven Spielberg and Tom Hanks on The Terminal.

For some reason, I started to think about Anvil. I had last seen them in 1986, and hadn't heard of them since. They had peaked in the summer of 1984, when they had played with Bon Jovi, Whitesnake and Scorpions. I found a dodgy-looking website and fired off an email. Within an hour, Lips had replied. "Hey, Teabag! We thought you died or became a lawyer." Lips flew to LA, where I now lived. He was balding, but his sartorial style was unchanged: leather, denim, Anvil T-shirt. They had been resolutely ploughing the same furrow, releasing album after album – 12 to date – and in their millions, people weren't buying them.

After each flop, Lips and Robb, now the only two remaining original members, would try to figure out where they'd gone wrong. On the cover for Strength of Steel, the band had swapped their black leather for red, which, they found out, "alienated their fanbase". The album hit 218 in the charts. They had gone from playing gigs in front of 20,000 people to playing in Detroit in front of one person. And that was a diehard fan for whom they had waived the entrance fee. It never occurred to Anvil to cancel the gig.

"The true majesty of Anvil has not yet been recognised, dude," said Lips.

It was that "yet" that got me. What was 25 years of humiliation and setbacks? Lips and Robb were now in their fifties, family men. But they were still optimistic about fulfilling their ambition to be rock stars. There was a great film story there. And with Anvil's biggest tour in years weeks away, I knew we had to start shooting immediately. My powerful Hollywood agents told me I was mad. I sacked them and hired a crew to make Anvil.

Six weeks later, I was at the Monsters of Transylvania heavy-rock festival a few miles from Dracula's castle. We trailed the band around Europe on their disastrous tour. At 5am one day, we ran out of petrol on a bridge between Bulgaria and Romania. When Lips relieved himself in the snow because the van's toilets were blocked, he was arrested by border guards who had recorded it all on film. In Italy, the band reversed their van into a police car. The low point may have been after a gig in Prague when the promoter tried to pay the guys in goulash. Or maybe it was the show at which they sold four T-shirts and used the proceeds to buy food. Or it could have been when we got lost in a pitch-black, freezing Romanian forest. In the morning, we found one of the vans was five feet from a sheer 100ft drop.

"Holy shit, dude," exclaimed Robb. "Anvil would have died in Transylvania. What a great rock'n'roll ending."

A few weeks into the tour, my cameraman, Chris, confronted me. "I need to know," he said. "Are they actors? Please tell me they are actors."

I realised my crew thought we were making a Spinal Tap-type spoof, so I knew we were in good shape. Robb and Lips thought we had the greatest movie ever made. We took it to Sundance, and I couldn't believe the applause. The buzz grew. Michael Moore declared it the best documentary in years. Keanu Reeves presented the film at the London Film Festival. The Prime Minister's wife, Sarah Brown, also attended, because her brother, Sean Macaulay, was a consultant on the film. On the red carpet, Lips urged her to give the two-fingered heavy-metal salute, but she demurred. She did tell us that she loved the movie, though.

I'd set out to make a film about my friends and musical heroes, and by making a film showing Anvil's failure to make it big, we might have given them the exposure they need. Lips and Robb are struggling to take in that they are tipped to open Glastonbury this year. They've spent decades chasing dreams. But if you have dedicated all that time to the thing you love, maybe that's not chasing the dream. Maybe that's living it.

'Anvil! The Story of Anvil' is out now. The book of the same name, by Steve Kudlow and Robb Reiner, is published by Transworld in March