Spearritt will also be familiar to fans of ITV's science fiction drama Primeval, having played zoologist and reptile expert Abby Maitland since 2007 with the programme's latest series due to air this summer.
Late last year Spearritt took on the role of Lady Frances in Jessica Swale's acclaimed Southwark Playhouse staging of The Belle's Stratagem. That production brought Spearritt to the attention of casting directors at the National Theatre and she was recent cast in One Man, Two Guvnors.
Richard Bean's Whatsonstage.com Award-winning comedy opens at the Theatre Royal Haymarket tomorrow (13 March, previews from 2 March 2012) with a new cast fronted by Owain Arthur, taking over the leading role of Francis Henshall from James Corden, as well as I’d Do Anything winner Jodie Prenger and Spearritt's Primeval co-star Ben Mansfield.
The production continues at the Haymarket until 15 September 2012 when One Man, Two Guvnors will embark on its second UK tour playing dates in Blackpool, Belfast, Salford, Llandudno, Glasgow, Newcastle, Leicester, Leeds, Nottingham, Norwich and Cardiff.
How did you come to be involved in One Man, Two Guvnors?
I was doing a play at the Southwark Playhouse called The Belle's Stratagem last year. The casting director for One Man, Two Guvnors came to see the show and it was that which got me the audition. I went along to the National for my first audition, had a recall and taking the role was pretty much a no-brainer for me. I'd seen the show twice before and laughed hysterically from the start to the end.
The Belle's Stratagem was your first stage role after a considerable gap. Can you tell me about the production?
It was a really great thing. I'd been involved with television for the majority of my career and it was great to get back on stage again. It was great to build something from scratch, the play hadn't been staged for a very, very long time and working with like-minded people to create something that we all believed in was really good for the soul really. It was a great little venue and I had a great time.
Looking back at your credits your transition from S Club to regular television roles appears to have been pain free?
I wouldn't say "pain free" but I've tried to manipulate it so it seems that way. It's not just happened. I've been careful in terms of what I choose to do and what I don't choose to do. I think it would have been very easy to take a different route. I think it's possibly taken longer, but I've been very sure of where I want my career to be heading.
For me when I got the call from the National to be seen for One Man, Two Guvnors was a bit of a milestone in my career. It's where I've been aiming for. That was a very good day in my world. Especially with my background, which not dissing it, is completely different from that area of the performing world, it was happy days.
In The Belle's Stratagem you appeared alongside a very strong cast, can you tell me more about that experience?
I thrown in at the deep end really, the play did kind of scare me. Because it's a restoration play, I looked at the dialogue and thought "how on earth am I ever going to tackle that" but once I started reading it out loud I actually really enjoyed it. Then I went along and had a really good time getting my mouth round the text and just enjoying it.
It wouldn't have been something that I thought would be my next project but it was almost perfect because it was challenging me in the right way. It was a really positive thing. It was a great cast; great to be involved with such a high calibre of people.
Has One Man, Two Guvnors changed with the new cast?
It is inevitablethat it has changed because everybody's take on the characters is in some way different, adding their own flavour, making it their own. That was encouraged during the rehearsal process.
The original cast rehearsed for far longer than we did. We were going into something that already had been a hit and already worked as a piece. We were able to just slip to the blocking and give our own performances. It was completely encouraged and allowed to happen. It's been a really creative process from that point of view.
It'll be interesting to see how different people find it, particularly if they've seen it before. Everyone says how different it is.
Was there a pressure to stepping into the shoes of the previous West End cast?
Of course there is a pressure there and it's kind of scary that we might not be executing it in the way that the original cast did but it's such a hard show not to enjoy, that the next minute you're in song and those feelings are kind of taken away.
It's a really good team. Everyone is adding their own ingredients and it's a great team effort. Everyone is doing such a fantastic job. It's just great to be on stage with everybody, who individually is doing a great job in a different way.
There is a lot of music in One Man, Two Guvnors, was that something which drew you to the piece?
The music has been an absolute joy. I completely am in love with music, so to have that going through the show, and most of it is so hilariously funny, is amazing. I do the chest slapping and stuff like that, and to be out there singing with two other girls - Gemma Whelan and Jodie Prenger - and to dress up as the Beverley Sisters, it is an absolute joy.
It's so much fun and then coupled with the costumes. Naturally I have the smallest amount of hair in the world so my wig is a godsend. I feel extremely lucky to be able to put it every day. It completely transforms you and how you feel.
You're working alongside Jodie Prenger who is known for her musical roles and your Primeval castmate Ben Mansfield
Jodie Prenger is the perfect casting for Dolly. When I heard she was in it I could immediately see her in the role. I was quite excited to get on stage with her. Ben Mansfield being in the cast was a complete surprise, but then makes total sense and again he's perfectly cast. He's incredible funny. When I found that we both had the job it was crazy news.
Is Primeval your highlight looking back at your TV work?
Absolutely, playing Abby Maitland is definitely a highlight. That whole period of my life is just really special. From a career point of view and from a life point of view, because I met my partner on the show and that was really special. Playing that character for that length of time and to be involved with something from the start, right up until the latest series which is coming out this year. That is really close to my heart.
I suppose from back in the day, getting a BRIT Award was a highlight. I don't quite know how that happened, in those days that was pretty up there and now I feel that I'm entering a different phase. One Man, Two Guvnors is a highlight in it's own way and is in every way just as shiny.
You place great importance on the path you career and that has obviously served you well. Where should we expect to see you in the future?
I would love to do more theatre, I really would. It's hard to say. I've only just started this job, and I've so enjoyed the process, getting the time to rehearse, getting to know people. You feel more part of a team in theatre, I think.
I feel really lucky to be doing theatre right now but to possible be able to dip between theatre and TV, that would be amazing. At the minute I'm completely loving doing the theatre.
It sounds like before taking part in The Belle's Stratagem you were pining to do more theatre?
My first ever job was a production of Bugsy Malone in the West End with National Youth Music Theatre. That was a bit of a crazy time. I was one of the six 16-year-olds from all over the country who came to London. I'm a country girl from a small town, I came to London to do this show and I was in a flat, living in London, with my other friends. I had the time of my life for three months.
That was the first thing which made me fall in love with theatre and it was from that job that I got an agent. It was soon after that life took a completely different turn and I went into the pop world.
With you background should we expect to see you in musicals?
I would probably say more straight stuff. I love the amount of musicality which is involved in One Man, Two Guvnors. I watched Backbeat recently and had my eye on Astrid and thought "I wouldn't mind playing that part in one day". I also had my eye on Legally Blonde for a while, which is a massive, massive stretch. I'm a lot more comfortable in the straight stuff really.
Have you got any dream roles? What are your plans for after One Man, Two Guvnors
I haven't got a clue about what's going to happen after One Man, Two Guvnors, that's six months away, and I'm not in a position to know what I'm going to be doing afterwards.
I would like to be involved in some new writing and maybe do something at the Soho Theatre. I would love to do something contemporary soon.