Killian Donnelly (foreground) as Deco
Killian Donnelly (foreground) as Deco

How have the previews been going?

They've been going great. I know it's a cliché to say "it's all been brilliant", but I've been involved in shows that are used to getting standing ovations, whereas with a new show you really don't know what to expect. So, to get a standing ovation every night and get people dancing in the aisles has been amazing.

It's not being billed as a jukebox musical - what sort of show is The Commitments?

It's really a play with music, in that the only time we sing is when we're trying to be a band. So at the start of the show we're atrocious at playing our instruments and then you see the moments when it all starts to gel. We perform songs like "Knock on Wood" or "Mustang Sally", but in the context of the story. Only at the end does it really turn into a concert.

How does it compare to, and differ from, the book and the film?

To my mind the show takes the best bits from both, in that you get the speed of the dialogue and the rudeness and the crudeness of the book, coupled with the music of the film. So it's taking these elements to make something brand new. Hopefully if you like the film or the book, or even if you don't know either of them, you'll enjoy the stage version.

Is Deco a role you've long had an eye on?

When I got a call from my agent saying "there's a workshop for a show called The Commitments", I said "I have to audition for this". I even cancelled a holiday to Greece so I could go. The one instruction at the audition was "don't sing anything from The Commitments", but I found out too late and had already bought the songbook, so fotunately they let me sing "Midnight Hour". I wanted it so, so much, even though I tried to play it cool!

Tell us a bit more about Deco

He's the most obnoxious, big-headed, arrogant prat that has ever walked the earth, but he has the gift of an incredible soul voice. Jamie Lloyd [director] was keen for us all to write back-stories for the characters, and I like to think he grew up on a council estate, is probably one of eight kids, and had a pretty tough childhood. So as a result the only person he'll listen to is Jimmy Rabbitte [the band manager], because he's the only one who ever told him he had a gift. But all that said, he's still a prick, and Jamie encouraged me to make him more of a prick.

Can you relate to the story and the era it depicts?

I was born in '84 so I don't really remember it, but I spoke to my Dad and my brother about the period. And in the summer I took a drive around Dublin, which isn't like it was then, but it was still good to revisit the streets. Having Roddy [Doyle] around is very useful because we can ask him what the locations depicted in the story are based on.

What's Roddy like to work with?

The man's a genius but he's so down to earth. And he makes you feel like such a wanky actor because you'll ask him, "what's Deco based on?", and he'll reply something like "I made him up, he's in me head." And that's what's brilliant about the book - he lets his readers put their own interpretations on the characters, he never gives too much away. Sometimes I've asked him 'can I say this?' and he's said 'no, because Deco wouldn't say that', but generally he's very open to change.

And Jamie Lloyd's another fantastic talent

During the workshop I was amazed at how calm and collected he was, and I couldn't believe it when that continued during rehearsals. He's so calm, and that just washes across the entire company. Plus, I can't believe he's only a few years older than me. I found that out the other day and I was gutted! He's achieved so much already.

Among the cast you're relatively experienced

Yeah - I was called a 'veteran' the other day and I couldn't believe it! But I suppose I have done a few shows like Billy Elliot and Les Mis, whereas some of them are getting their first West End credit. But when you're starting anew on a new show you're all on a blank canvas. And Jamie was keen to remind us that there's ten people in the band, on stage at the same time, working as one. It's very much an ensemble piece, there's no 'star' as such.

What was your route into theatre in the first place?

Growing up I always wanted to be a primary teacher, and joined the local musical society as something to do in the evenings. And then one of the directors advised me to go to London and make a go of it. I knocked on about 20 agents doors before one signed me, and they mentioned there was an audition for Les Mis. So I went along to that and the rest is history really. I often call myself an 'unprofessional professional', because in rehearsals I still wander around like a lost child.

Finally, what would you say to entice people along to see The Commitments?

I'd say if you want a great night out, come to see The Commitments, and if you want a brilliant piece of theatre come and see The Commitments. It's something you're definitely going to be telling your friends about, and it's unlike anything else out there at the moment. Also, I guarantee you won't get "Try a Little Tenderness" out of your head for a week.

The Commitments premieres at the Palace Theatre tomorrow (8 October 2013) - look out for our coverage including first night photos and our round-up of reviews