Chicago in the 1920s. These are violent, troubled times, where danger lurks in shadows and gangsters run the show. It's also the beginning of a burgeoning celebrity culture, with the growth of Hollywood movies, popular music and a booming media industry combining to nurture a new breed of megastars. Sensational stories sell, and journalists prowl the streets, sniffing out the juiciest morsels they can find in the hope of making headlines...

Living and working among them is Maurine Dallas Watkins, a young reporter for the Chicago Tribune. It's while covering two high-profile murders that she sees how celebrity obsession is changing the way that courts treat criminals, prompting her to write a play based on her stories. Nearly 50 years later, the play would be transformed into what would become the longest-running American musical on Broadway, outdone only by the British Phantom Of The Opera.

Forty-one years after its smash-hit US debut, Chicago is undertaking a brand new UK tour, arriving at Birmingham's New Alexandra Theatre in time for Christmas. The production's fabulous cast includes EastEnders' John Partridge in the starring role of slick, quick-talking lawyer Billy Flynn, a character he imagines might have carved a slightly different career were he around today...

“Billy is the King of Spin,” explains Partridge. “I guess today's equivalent would be something like a PR Guru. It's his job to raise the profiles of our two loveable murderesses, Roxy and Velma, to ensure their names stay in the press and ultimately get them let off for their crimes. It's a dream of a part. I get to flick the hair, shine the shoes, put on the tux, and get draped in feathers!”

Some things change while others stay the same. The internet and the explosion of reality TV might have affected the way we interact with our celebrities today, not to mention swelling their ranks enormously, but ultimately, our culture is a continuation of the one that Watkins saw emerging close to a century ago.

“It's very topical now,” Partridge continues. “Even when the musical was conceived back in 1975, I don't think we had any idea of how celebrity culture would explode. It's everywhere now - it's in people's homes, on television, in magazines and on social media. There's no getting away from it. I think that's part of the reason the show has this lasting appeal - the story is very contemporary in its nature but it’s dealt with in this old-school way.”

Doing justice to the powerful story and its compelling characters is paramount in this production, which has been stripped clean of all the flashy and sometimes shallow extras that are often part and parcel of large-scale musicals.

“It's a very stark, minimal set that we have, which really focuses your attention on the narrative and the storytelling of the show. There are no scene changes and no costume changes, which is quite unusual for a musical and quite brave. Often, shows rely on sets and costumes, perhaps because they need to, whereas Chicago is so power ful that it doesn't need all the extras. It does mean audiences have to really pay attention, though, because they're not being directed by the set. That's what makes it such a great piece for an actor - it means that we're in charge of taking the audience on the journey, rather than external things doing that for you.”

Rest assured, however, that the show will still look and sound fantastic. It might not be conventionally flamboyant, but it's still undeniably stylish in its own way, packed full of iconic musical numbers and incredible choreography.

“It's a very clever, highly stylised musical. The choreography and the dialogue and the songs are all woven seamlessly together so that everything is very fluid, and there really is something for everybody. The score is legendary - you couldn't ask for a better one - and our band is absolutely exceptional. People often forget that Chicago has a jazz score, and in this tour, we have an amazing 12-strong jazz band who’re very much part of the show. In my opinion, they're worth the ticket price alone! We also have one of the sexiest ensembles of dancers that you’ll see on stage this Christmas, trust me!”

With its clever script, intricate dancing and stand-out musical numbers, you might think that such a complex and demanding show would make hours of practice and rehearsal an essential, but for Partridge, fresh from his stint on Celebrity Big Brother, time was a luxury not afforded in this case.

“I actually only had three days' rehearsal, which I do not recommend!” he laughs. “It was scary. I came out of the Big Brother house on the Friday, did all the press that went with that, and then I had my first rehearsal on the Monday. When we opened on the Wednesday, there were a lot of grey-faced producers standing in the wings thinking, 'Oh my God, is he gonna pull this off?' But fortunately musical theatre is in my blood. I went into Cats when I was 16 and I'm now 46, so it's something I've done for a long time. And, I'm pleased to say, it all came off. Funnily enough, I'm going to be going through another hair-raising rehearsal period shortly - we finish Chicago on 31 December, and then my next show, La Cage Aux Folles, opens in Oxford on 5 January. It seems to be becoming what I'm known for!”

Of course, it may have helped that Partridge already had some familiarity with the role, having initially been offered it back in 2010. But since beginning this year's tour, he's had plenty of time to get to grips with Billy, continually learning, finessing and developing the part.

“When I was first offered it in 2010, I turned it down because I didn't think I had the maturity, but when I knew the show was coming round again, I actively threw my hat into the ring. Luckily they were very receptive and offered me the part straight away. I've had a wonderful time doing it - it's a great company, we've really grown together, and we're all still constantly finding new ways of playing it. In Birmingham we're also going to be joined by Mica Paris, and it's always lovely to have a fresh viewpoint on something, especially at this stage in the tour.”

Partridge is no stranger to working during the Christmas season. Over the last five years, he's appeared in various pantomimes, including Birmingham Hippodrome's Snow White And The Seven Dwarfs in 2013.

“This is the first year in a while that I won’t be slapping my thigh and mugging outrageously to the audience for laughs! I'm afraid working over Christmas is all part and parcel of being an actor - the holidays are our busy times, so we take our vacations at other times of the year. But all my family are going to come and watch the show on Boxing Day - if I've got to do two shows on Boxing Day then they can all come and see me!” 

And while treading the boards instead of flopping in front of the telly at the height of the holiday season isn't for everyone, Partridge is looking forward to being back here for another Christmas show, having thoroughly enjoyed his stint in the UK's biggest and best panto.

“Every audience is different, and every town you visit has a different sort of feel. Some are harder than others, but others are on their feet the minute you come out on stage! I've always found the audiences to be very warm and receptive in Birmingham, so I'm glad to be coming back.”

Chicago runs at Birmingham's New Alexandra Theatre from Monday 12 to Saturday 31 December.