Image caption Silibil N Brains pretended to be from California when they were actually from Dundee

You are Scottish and you want to be taken seriously as a rapper, what do you do? In the case of Gavin Bain and Billy Boyd, they pretended to be American and lived a lie for three years.

Gavin and Billy, who met at college in Dundee, wanted to be the next Eminem but instead they were derided as "the rapping Proclaimers".

Back in 2001, being Scottish rappers got the pair laughed out of the room when they met record company executives in London.

"Thirteen seconds into the first track and they just started laughing," says Bain.

"We were just thinking 'what's all this about?'. It was heartbreaking."

"Real" rappers did not come from Scotland, they were told.

So they went away and came back as "Silibil" (Boyd) and "Brains" (Bain) from a small town in California who met at a rap battle contest in San Francisco.

Image caption Billy Boyd and Gavin Bain at a screening of the film about their hoax

Their new personas suddenly attracted interest from the London execs but in order to maintain the deceit they had to lie to everyone - to fans, to fellow musicians and to the record industry.

They told record company bosses they hated US President George W Bush and wanted to make it in the UK but Bain had never set foot in America.

Boyd says: "We created a back story. We created these monsters, these American egotistical characters and we became these characters."

He says as long as they acted loud enough and played crazy enough, it did not seem to matter.

Image caption Silibil N Brains on MTV in 2004

It was a massive lie which lasted for more than three years, during which time they were taken on by Jonathan Shalit, the man who discovered Charlotte Church, secured a record deal with Sony, appeared on MTV, partied with Madonna and played on a UK tour with Eminem.

Appearing with D12 (Eminem's hip-hop collective) was one of the many times when the lie almost unravelled.

Image caption Silibil at the Brits with comedians David Walliams and Matt Lucas

Silibil N Brains had claimed to be friends with the Detroit rappers so when they saw Proof and the rest of D12 doing a sound check on the first night they could not risk their cover being blown.

The pair high-fived Proof and gave him a big hug, declaring it had been a long time since they met.

The rapper was too stunned to disagree and the impression of their hip hop credentials was maintained.

Boyd's girlfriend, who still lived in Dundee, was one of the few people who knew of their deception.

He says: "She'd come to London and we'd be out shopping and the phone would go and it would be someone from the office. I'd have to snap into American straight away."

The boys were "keeping it real" by living a lie but they were desperate to come clean.

They recruited band members from Scotland and South Africa and tried to take their music in a punk rock direction, much to the bemusement of the record company which had signed two west coast rappers.

Image caption The stress of keeping up the pretence took a great toll on Silibil N Brains

The strain of the worry and the constant partying began to take its toll.

Every day for years, they had pretended to be American. Bain even had a Texan girlfriend who never suspected a thing.

But Bain's mental health was suffering and he also had a painful stomach ulcer.

He says the pressure of the lies and the paranoia was becoming too much.

"You tell one lie and it will become a million lies," Bain says.

Boyd had also had enough and eventually packed up and went back to Dundee.

The Great Hip Hoax was over but the story is now being told in a film, which is on general release.

The director of the film, Jeanie Finlay, says: "The idea of someone denying their Scottishness to get what they wanted seemed a bit crazy to me.

"Imagine denying a huge part of who you are, what is the impact of that?

"The characters they created came with a huge moral compromise. They created people they didn't actually like."

Ms Finlay adds: "I like this idea of a lie growing arms and legs and running away."

BBC Radio Five Live movie critic Mark Kermode says: "You see these people doing these west coast accents and think how could anybody take them seriously but astonishingly they did.

"The underlying message of this seems to be that, surprisingly enough, the music industry is perhaps more vacuous than you might have expected."