What's the use of being a sensation if you never get the opportunity to show it? In Jule Styne and Isobel Lennart's iconic 1963 musical, Funny Girl, the unconventional Fanny Brice makes it big against the odds, thanks to a winning combination of hard work, determination and a lucky break.

She's not the only one. When leading lady Sheridan Smith was forced to take time out from performing in the show's West End run last year, understudy Natasha Barnes was called upon at short notice to step up to the plate. Audiences who'd booked tickets in the hope of seeing Smith went in sceptical - Sheridan's shoes are undeniably hard to fill - but almost every one of them came out converted. As Fanny Brice would have it, Barnes was just an untried bagel on a plate full of onion rolls - all it took for people to be blown away by her was for someone to give her a chance.

“I've understudied for a few things before, and for whatever reason you don't always get to play the part,” says Barnes. “So just having the opportunity to go on is amazing, but even though I'd done all the work in the rehearsals, I'm not sure how prepared I actually was. On the first night, I was just surprised I got through it, and then when everyone stood at the end, it was one of the best moments of my life. It was what I've wanted ever since I was little, and to see that people were really enjoying it was really special. I'm still grateful for it now.”

The reviews were gushing, declaring her in no uncertain terms as good as Smith, and heralding her as a bright new star in the musical theatre firmament. So well did her performances go down that as the production embarks on a UK-wide tour in 2017, Smith and Barnes will share the role between them, alternating performances at different venues. To some extent, the pair each make the role their own, but whomever they see leading the show, audiences are guaranteed a real treat.

“I think my take really came out of the West End run. When I first started out, I did quite a close representation of what Sheridan did, until over time the character sort of became mine. The tour is just a chance for both of us to bring what we did in London to the rest of the country, while still keeping it fresh and making sure it's just as special as the first time round.”

Of course, Smith's isn't the only performance Barnes has had to live up to. For many, the show will be forever associated with Barbra Streisand, who originally played the part both on stage and screen. It's partly this, thinks Barnes, that's kept directors from taking it up again for decades - prior to last year's run, it had been an incredible 50 years since Funny Girl last showed in the West End.

“When you have somebody as iconic as Streisand, you really have to find the right person to follow them. I think Sheridan is one of the greatest female comedians of our generation, so it was very much her work that was the starting point for this production. But it’s interesting that it's made a comeback now, because it’s being referenced in a lot of things, and also it's a time when you have all sorts of people, like Amy Schumer, really getting their moment to celebrate the funny in being female. I think it's great that as actresses we have more opportunities now to take centre stage and play roles that are a bit silly.”

Then there's the fact that the story is semi-biographical, inspired by the true story of the real-life theatrical gamechanger Fanny Brice who, in the early 20th century, had to fight against preconceptions of what a female performer should and shouldn't be.

“She's a funny old character to play because she was a real person. You don't want to do an impression but there are certain things you have to honour in the performance - like she was known for really big facial expressions and for being larger than life. She's a very strong woman, a real fireball and quite ahead of her time. She's also very funny and really wears her heart on her sleeve. She doesn't hide anything. So it's all about trying to be as open and as full of light as you can be.”

That aside, in many ways the part might have been tailor-made for Barnes. The parallels between her own and Fanny's journeys to success have not escaped comment so far. It's also a fantastic part for an emerging talent in terms of showcasing great range, with Fanny growing steadily older and wiser as the play progresses. The story covers several years of Brice's life, from her teens through to her thirties, with Barnes falling right in the middle of the range.

“I did worry about it a bit at first, whether or not I could play someone older than me. But it's a really well-fleshed-out part, and you do get a sense of moving through time with her - it's something that happens very naturally with each song. The show picks up with the older Fanny sitting at her dressing table, and then shoots back to show her at age 15. And luckily, from that point on, it’s straight through until the end of the show, so there's not too much jumping around in time. I have to say that the first 20 minutes of the show are a bit of a sprint because when she's younger, you have to be much more energetic and use your body a lot.”

For Barnes, who can remember singing songs from the show at the age of six or seven, Funny Girl has been the opportunity of a lifetime, and something for which she feels she's been preparing for almost as long as she can remember.

“I think I first watched the film with my nan on a Sunday afternoon. At the time, I was really young, and all I thought then was, 'God, that lady's got a good voice'. The film and the show do have some differences, though - a lot of the book was rewritten, and they've worked quite closely with the estate of Fanny Brice and the original writers. I think it feels a lot more modern now - it snaps along at quite a fast pace, whereas the film was quite long.”

Naturally, being lauded as the next big thing in musicals has taken some getting used to, and it's not just the publicity that's been a shock. There's the enormously demanding schedule, too. Fortunately, the West End run has left Barnes much better prepared for this year's tour, furnishing her with the wisdom and experience to ensure she doesn't burn out when she hits the road.

“It's a bit like driving a car, when you're learning how to make the engine run as smoothly as possible so that you don't stall it or blow it out or overheat it by putting it through too much. After the first night, when I woke up the next morning, I felt like I'd been hit by a bus! I was so tired and couldn't imagine how I was going to do it for eight shows a week - that's something you have to learn to manage quite quickly. But I think you have to do a few shows, get it wrong a few times, maybe work a bit too hard or be a bit under-energised until you can get to that sweet spot where you can give it 110% but not exhaust yourself so much that you can't do it the next day. I mean, on a matinee day you're singing nearly 28 songs, which is huge for anybody, so it's just about pacing yourself and treating it like a marathon rather than a sprint.”
This will be the young performer's first time touring, and she's certainly looking forward to the fresh sights and new experiences her visits to the Midlands and elsewhere will bring.

“I've never done the living-out-of-a-suitcase thing before. I'm actually really looking forward to being on the road because I get very into my work. I think it's a lot easier to get fully inside a show or a role when you don't have the distractions of everyday life around you. But also I'm looking forward to seeing a bit of my country, especially Scotland and all the places I haven't been to, including Stoke. I keep looking up things to do - it feels a little bit like being Alice in Wonderland.”

Funny Girl - starring Natasha J Barnes - shows at the Regent Theatre, Stoke-on-Trent, from 28 March to 1 April, and at the Wolverhampton Grand Theatre from 24 to 29 July. 

It visits Birmingham Hippodrome from 8 to 13 May, with Sheridan Smith in the lead role of Fanny Brice.