‘Cello Metal’ is a phrase that, at best, suggests an awkward music press portmanteau and at worst a horribly contrived novelty genre.

Yet the band who can lay claim to having made the first introductions between these two words, Finland’s Apocalyptica, are an genuinely organic concept; seeded during a just-for-fun friendly jam over some Metallica tunes in 1993 and growing ever since, under the gawping gaze of a music world feeling not unlike the zoo keeper who witnessed the result of the common donkey getting into bed with the exotic, wild zebra become his star attraction.

The zonkey of the musical world, if this analogy must be continued, Apocalyptica’s tale is proof that truth really can be stranger than the science fiction of genetically engineered media hype, though the band’s unlikely rise to fame still reads like a fairy story.

Founder member Eicca Toppinen (who is joined by two fellow cellists Pavvo and Perttu, and drummer Mikko) gives us the short version.

“When we started the band we had no expectations,” he says, “we didn’t have a band actually, we were just a bunch of friends playing Metallica, and then we were asked to do an album [1996’s Plays Metallica by Four Cellos]. We said, ‘okay, let’s do it for fun, one album’. And suddenly it became a success and we started to tour and then we realized the sound was different so we thought let’s do another one, let’s make it better than the first one. We released Inquisition Symphony and then we turned to original songwriting, and after that we started to add additional elements into the music, like drums, bringing singers in, all this stuff. It’s been a big evolution from the beginning.”

Today the band’s cerebral melding of classical music and contemporary metal has found them a respectable perch up the evolutionary ladder of the music business. At the time of speaking Toppinen is in Oxford, about to begin the UK leg of a tour that has taken his band across the globe over the previous year to play in the region of 160 shows. More than 70 of these have been on the stereotypically unbreakable soil of North America. Right now they have a single riding high in US rock radio playlists, and can count other achievements for 2008 as winning over audiences at Jazz festivals, and even the Finland-hosted Eurovision Song Contest. It’s testament to the fact that, theoretically at least, the audience for a group that refuses to confine itself to one genre is limitless.

This has not always been the case however. The equally likely fate of a band too unique to fit established markets and consumer demographics is, of course, that they fall victim to conservative music biz minds that simply don’t know what to do with them. When Apocalyptica released their self-titled fifth album in 2005 via Universal - spelling a major label money and marketing boost that would mean ‘big time’ for the majority of groups - that was nearly the case.

“It was tricky with Universal, they never wanted to release the album anywhere, especially here in the UK,” sighs Toppinen, “it was hard times for us, so many albums Universal just refused to release and so it never worked out.”

The good news is that Apocalyptica is reissued in the UK this month, and for cello metal virgins it provides some worthwhile background listening before approaching the band’s most recent evolution, the 2007 opus on Jive Records, Worlds Collide.

“The first ten years was basically a big search for identity,” Toppinen says, “starting as a covers band and then doing our own thing and trying to find an identity took time. [On Worlds Collide] we thought ‘okay, maybe now it’s time to open the doors to the outside world a bit and see what we can create together with other cool people’.”

With this last comment Toppinen refers not only to the impressive list of new names Worlds Collide adds to Apocalyptica’s roster of guest vocalists, but to the fact that this was the first record since last covers album Inquisition Symphony on which they enlisted the services of a producer. During that period of seeking identity every aspect of recording and production was handled by the band themselves. Here that passed that mantle on to Rammstein production mastermind Jacob Hellner. Trusting the taste of past collaborator, Rammstein frontman Till Lindemann, Toppinen admits “[Jacob] is coming from a completely different perspective, in that the way he sees music and his background is totally different to ours, but we thought ‘okay, it might be a cool mixture to work with such a guy!’”

Against the odds of record contract clauses and constant touring commitments Toppinen and co also succeeded in pinning several high profile metal vocalists down to record tracks on Worlds Collide.

“It’s a different approach with every collaborations” he says. “Sometimes we have songs where the lyrics are already written and we just need to find a person with the right sound and character to carry the vocals. This is what we give to the busy people like Corey Taylor [the Slipknot / Stone Sour vocalist sings on ‘I’m Not Jesus’]. It would have been impossible to write with Corey for example, he’s so busy all the time with Slipknot and Stone Sour that there wouldn’t have been time to start from scratch, it was easier that the song was done when he stepped in.

“With S.O.S it was a very obvious track for a female vocalist. It started off as an instrumental track, then we started to think ‘what would happen if we add a vocal to that’. Then it was very obvious it needed to be a female vocal, and then it was a case of thinking ‘okay, who are the great female voices in the rock scene?’ and Cristina [Scabbia, Lacuna Coil] was very obvious.”

But they have cellos. Can they be metal to the legions of traditional metal fans not used to such a thing? Toppinen has an answer.

“What is metal to Apocalyptica? That’s a good question,” he considers. “We actually had this conversation a lot when we were doing the last album and we came to the conclusion that metal is an attitude. For me, I grew up with thrash bands, like Metallica, Slayer, Pantera. At that time that was the most rebellious thing happening in music. But now, at 2008 metal has lost a lot. A lot of metal bands are just pop in attitude, only with distortion and double bass drum and that to me isn’t metal at all. The distortion doesn’t create metal, and the double bass drum doesn’t mean metal. Before, metal was a creative and innovative thing and that’s what made metal for me”.

If that is true, then the case is closed. After all, they don’t come much more innovative than Apocalyptica.