With four studio albums under their belt, and coming straight off the back of a packed summer full of festivals, Bellowhead are going back on the road for their biggest UK tour to date.

More ambitious than ever, the foot-stomping 11-piece – who come complete with brass and string sections and an inventive percussionist – have become the flag-bearers for contemporary folk music. And as they embark on a 19-date tour, which calls in to Open in Norwich this Friday, they clearly show no signs of slowing down.

The arrival of album number four, Broadside, was much-heralded earlier this month, with the band once again turning to legendary producer John Leckie, who has worked with Radiohead and the Stone Roses. The new release sees Bellowhead adopt a darker, more theatrical, edge to their music.

'The arrangements have come very naturally for this album, it's a very natural sound,' said singer and fiddle player Jon Boden, who had the initial spark of an idea to set up a big folk band with accordion player John Spiers back in 2004.

'It's working well, and it seems to have come out of nowhere. This is the album I'm most proud of as it was harder to do. It's a musical achievement, and we're going in new directions. It's my favourite album, and I'm very proud of it.'

With an ancient canon of folk songs to choose from, Bellowhead take the familiar and turn it into something big, bold and bouncy.

'We do cover some dark material, but only comically dark,' said Jon. 'There are some very dark themes in the folk canon which we wouldn't want to make light of, but we cover the stuff that has a dark humour, rather than being horrific. We still have a sense of humour, and the songs lend themselves well to it.

'The song I'm most proud of on Broadside is The Old Dun Cow. It's a very well-known song and I've been thinking for a long time that we ought to do something with it, but didn't know how. I'm very pleased with it, as it's very complex.

'My favourite song on the album though is Black Beetle Pies, it's the most Tom Waits-ish we've got.'

As a musical conglomerate of 11 musicians, drawn from all over the UK, Bellowhead certainly have strength in numbers, but can it sometimes be tricky to get the songs to come together in rehearsals?

'There's nothing we've really struggled with. We will be dropping a couple from the set for logistical reasons; we'll alternate the songs over the tour as we don't want to over-burden people. But we'll be doing about 90pc of the new album every night. We have to make sure we are pretty well prepared at every rehearsal. We do a lot of work beforehand, otherwise with 11 of us it would take forever.

'The Wife of Usher's Well is one we've not done live before, and it's the most different, so it'll be exciting to perform it and see how the audience reacts. We have a great live engineer so it'll be interesting to see what she does with it.

'We dropped some of the new songs into our live sets over the summer and they seemed to go down well. It's a different relationship with the audience, but now they've had a chance to listen to the album it'll be interesting to see what the audiences bring in terms of their expectations.

'The initial sketching out of the arrangements are mostly done by me and Pete [Flood, percussionist], but when it comes to rehearsals it's a whole band effort. The band make it come alive,' added Jon.

But not everything makes the final cut. There are two extra tracks which didn't make the album, available to download, which were arranged by band members Paul Sartin and Justin Thurgur.

'They are very different sounding, arranged by different people, and are both well worth a listen,' said Jon. 'They will be great to play live. The tunes didn't quite bed in with the rest of the album, so producer John Leckie decided not to include them, but they are a very sophisticated-sounding orchestration.

'Saxophonist Brendan Kelly also had a few arrangements which didn't make the album, but they might be on the next one. There are contributions from everyone.'

When the mighty Bellowhead bus rolls into Norwich, the audience will no doubt look forward to the many Norfolk references in their songs, including Fakenham Fair and Yarmouth Town. But do any of the band have connections with our fair county?

'Not personally, but it's a very important county in terms of folk music,' said Jon. 'Lots of songs were collected from Norfolk as the county was able to hold on to the traditions for a lot longer. My musical hero Peter Bellamy came from Norfolk, and he collected a lot of songs, so Norfolk is well represented in the folk scene.

'We haven't been to Norwich for a while – we can't come to both Norfolk and Suffolk, and Ipswich has won the last two years. But it's great to come back to Norwich – it's actually one of my favourite cities. We've got a tour bus, and we often wake up in the town we're due to play in, so it'll be great to be able have lots of time to kill in Norwich.

'What we are hoping to do after each gig is an acoustic pub gig. It'll take a lot of organisation, and we'll be relying on the audience to recommend some pubs to us. We also need to ensure that the pub can stay open until 1am and we're not sure how long we can stay around for, before heading off in the bus. But once we sort out the logistics, we'd love to do some post-gig pub sessions.

'Norwich would be a great place to do that.'

Bellowhead come to Open in Bank Plain, Norwich, on Friday at 7.30pm. Tickets, �18, are available from the box office on 01603 763111. Over 14s only.