It began as a mad idea to recreate one of the most popular pieces of music of the past century on two acoustic guitars in a living room in a town just outside Sydney.

Now, after becoming one of the successes of the Edinburgh Fringe last year, old school pals Daniel Holdsworth and Aidan Roberts find themselves being part of the 40th anniversary celebrations of Tubular Bells, the album that launched Richard Branson's Virgin record label and made its composer, Mike Oldfield, a very rich young man.

Holdsworth and Roberts are a little young to remember Tubular Bells's release but the album became a favourite in their youth as Holdsworth bought up bundles of discarded vinyl in the wake of the CD revolution and Roberts retained memories of his parents playing it on long car journeys.

"We've known each other since we were kids but we hadn't seen each other for a while when I moved into a house quite close to Danny in the winter of 2008 and invited him round," says Roberts. "We had a few glasses of wine and I said: 'Do you remember Tubular Bells?' Danny said: 'Of course', and we started to play bits of it. Then we decided to learn it all and the idea grew into a live performance the following spring."

They approached the Clarendon, a popular local small-scale theatre-cum-restaurant-hotel and asked for a quiet night so they could try out the by-then many instrument changes in front of a few friends and family members. The Clarendon responded by offering them Good Friday and instead of the expected 30, they made their Tubular Bells for Two debut to a packed audience in three figures.

"It was nerve-wracking," says Holdsworth. "We were still refining the music – we're still refining it even now; we keep going back and discovering small details and bringing them into the performance – and it was quite rough. But the audience were really willing us on and they'd actually laugh when we got through a tricky change-over successfully, although the sight of two agitated musicians struggling with more than 20 instruments and feverishly layering passages through loop pedals in real time was probably quite funny in itself."

From the start, the boys were keen to capture not just the phrases Oldfield played but also the timbre of the instruments. Having played in bands since their teens and having released several albums, both with bands and solo, they're fairly resourceful musicians. Neither, however, plays flute but they were able to replicate the sound on a keyboard and the more they dug into the original recording, the more detail they realised they were going to have to take into account.

"Because it had been such a favourite with my parents, we were very aware that we were in danger of treading on peoples' feelings," says Roberts. "So we wanted to get as close to the original as possible. There's no official score as such and that meant that we had to kind of map out what happened when and we had to figure out how we were going to change instruments at specific points. It was a lot of work but the response we got on that first performance made us think that maybe we could take this a bit further."

Subsequent performances, including sold-out seasons at the Sydney Festival, Sydney Fringe Festival and the New Zealand International Arts Festival, convinced them that they had a special show on their hands. Even so, coming to Edinburgh for the Fringe was a big adventure that could have gone disastrously wrong. Instead, with a little help from a Bank of Scotland Herald Angel, the experience has opened the doors to Europe.

"People had thought from the start that we might be having a laugh at Mike Oldfield's expense," says Holdsworth. "And in Edinburgh, where there's a lot of comedy shows, I think there was a danger that we might be mistaken for a spoof. The audiences were great, though, and we got really good reviews."

The pair haven't actually consulted Oldfield, although they secured the necessary permission from his publishers, but following their Edinburgh run they discovered an interview in a magazine where the composer had been asked if he'd heard about these two Australians who were performing Tubular Bells.

"He said he thought this was 'really cool'. That's only two words but we'll take it as an official endorsement," says Roberts.

"We never expected to be appearing in London right around the time of the 40th anniversary of the album's release and the original Tubular Bells live concert. But we're really pleased that we can be a small part of that celebration. I can't think of many better jobs than touring around Europe playing music that you love – even if it is quite hard work."

"Yeah," agrees Holdsworth. "Even after more than 100 performances, we can't ever get complacent. But when we reach the part on side two of the original album where we have the Piltdown man chant and I get to sit behind the drums and rock out for a bit, that's a great feeling because we've almost made it to the end again and I can relax just a little bit."

Tubular Bells for Two plays Eden Court, Inverness, on Monday, May 27; City Halls, Glasgow, on Tuesday, May 28; and Kings Theatre, Edinburgh, on Wednesday May 29.