In the world’s longest-running play The Mousetrap, which is open at St. Martin’s Theatre and has been in London’s West End for 74 years, Cathryn Sherman understudies the role of Mrs Boyle and works alongside Georgina Fairbanks as Mollie Ralston, Cai Brigden as Giles Ralston and Joshua Riley as Christopher Wren, and the Agatha Christie play is currently directed by Ola Ince. For the 2016 UK revival of Stephen Sondheim’s Roadshow at Union Theatre, Cathryn played Mama Meisner, and the previous year, she played Helene in Henrik Ibsen’s A Doll’s House at Barons Court Theatre. Cathryn has had a long theatre career since training at Mountview, including working on Starlight Express at West End’s Apollo Victoria Theatre as a vocal booth singer, 84 Charing Cross Road as Cecily Farr, Les Misérables as Ensemble and understudy Madame Thénardier, and she was part of the Les Misérables 10th Anniversary Concert at the Royal Albert Hall in 1996 and the 25th Anniversary Concert at The O2 Arena in 2010. Early in Cathryn’s career, she toured the UK in The Sound of Music, and alongside theatre, she has been a backing vocalist on Lesley Garrett’s Travelling Light Tour. Talking to Cathryn, we found out from her about her time so far in Agatha Christie’s The Mousetrap at St. Martin’s Theatre in the West End, playing Mama Meisner in the 2016 UK revival of Stephen Sondheim’s Roadshow and being part of Les Misérables over the years.

For those that haven’t yet had the chance to see The Mousetrap, and without giving any spoilers, what can you say about the Agatha Christie play, and how would you describe Mrs Boyle (who you have understudied for a number of years)?

Agatha Christie’s The Mousetrap is a whodunnit that encompasses the genres of drama, murder mystery and comedy. It is set in a manor house that has been left to Mollie Ralston after her aunt’s death. She decides to open it as a guesthouse, and the play opens on their (Mollie and her husband Giles Ralston) first day of running it.

The other characters (Christopher Wren, Mrs Boyle, Sergeant Trotter, Major Metcalfe, Miss Casewell and Mr Paravacini) bring with them all sorts of intrigue, fun and personal emotional baggage. The play is full of shocks, deception and humour.

Mrs Boyle, I feel, is a misunderstood woman in many aspects. She is struggling to make sense of a life that is now very different to the one that she was used to a few years ago, and can seem to be quite abrupt and caustic, and fairly self-centred.

She is a wonderful character to portray, as there are so many facets to her personality. She is very forthright, and says things as she sees them.

As understudy Mrs Boyle, what is the character like to play and what do you remember from your first performance in the role?

Our contracts are for six months, so I have worked for six months on The Mousetrap, then had six months off to do other projects, and then another six months understudying Mrs Boyle etc. This is the fourth time I have been fortunate enough to work at St. Martin’s Theatre.

Mrs Boyle is great fun to play, as she runs the gamut from slightly disgruntled, to being upset, to emotionally drained over the course of the play.

My first performance was an amazing feeling. To be on stage with such a supportive cast in a play with a massive history was a real privilege. To hear the audience’s reactions to things that I had only rehearsed before was so special.

How familiar were you with Agatha Christie’s work before booking The Mousetrap and what is it like being part of one of her well-loved plays?

My mum had most of Agatha Christie’s books, so I grew up reading them, and I still do read them on the tube going into work. I loved all of the television versions of her works, particularly the David Suchet Poirot and Joan Hickson Miss Marple series.

To be part of The Mousetrap has always been a joy. St. Martin’s Theatre is a very special place to work. It really feels like a family, from every single one of the people who work there, from front-of-house to the full-time staff in different departments in the theatre, to all the members of separate casts I have worked with. I really feel a sense of history when backstage. It is an amazing experience, and one I feel very honoured to have.

What is it like working alongside the current cast, which includes Georgina Fairbanks as Mollie Ralston, Cai Brigden as Giles Ralston, Joshua Riley as Christopher Wren, Nicky Goldie as Mrs. Boyle, Christopher Wright as Major Metcalfe, Kate Handford as Miss Casewell, Stephen Ventura as Mr Paravicini and Thomas Dennis as Sergeant Trotter, and being directed by the new director – Ola Ince?

It has been lovely. Every six-month contract, the different actors portraying the characters bring something individual to their roles, which I believe keeps the show new and fresh. I have had the pleasure of being directed by three separate directors on The Mousetrap – Ian Talbot, Philip Franks, and now Ola Ince. They are all very different in their approach to the play and have each produced a slightly different show, but from the audience reactions, they have all hit the mark!

With The Mousetrap now in its 74th year, why do you think the show has stayed popular for so long and how did you feel joining the cast?

I think perhaps the reasons that The Mousetrap has stayed popular for so long have changed as the years have progressed. When it first opened at The Ambassador’s Theatre in 1952 – next door to where it is now at St. Martin’s Theatre – it was a production of a new Agatha Christie play. Her books were very popular and were consistently at the top of the bestsellers lists, so people wanted to see her plays.

As the years went by, the same reason existed, but now added to that is the remarkable fact that The Mousetrap is the longest-running show the world has ever seen. Some people come to see it to be included in that amazing history, and come away feeling that it still shocks, and there are some laugh-out-loud moments, which surprises some people.

When I joined my first cast, it was for the 70th Anniversary production, so I felt very privileged to be a part of something so unique in theatrical history.

What are you enjoying most about performing on stage in the West End in the world’s longest-running play?

I love the fact that the audiences are really engaged in the performances, and the on-stage casts have always been so supportive whenever any of the understudies go on. With everybody who works in the building feeling like one big family, it is always a real pleasure to go into work.

The understudies work closely together. Each week we have line runs, watch the show to check there have been no changes, and also have on-stage rehearsals with the amazing artistic director Denise Silvey. This contract, the understudies with me are Saranna Parlone – Mollie and Miss Casewell cover, Clive Marlowe – Major Metcalfe and Mr Paravacini cover, Ben Riddle – Giles Ralston and Sergeant Trotter cover, and Richard Parnwell – Christopher Wren cover and second cover Sergeant Trotter. There are also two floating covers: Barnaby Jago – Christopher Wren, Sergeant Trotter and Giles Ralston cover, and Jason Hall – Major Metcalfe and Mr. Paravicini cover.

How was it playing Mama Meisner in the 2016 UK revival of Stephen Sondheim’s Roadshow at the Union Theatre?

It was a wonderful experience. It was my first ever Sondheim musical, and everyone on stage and off made it a really fun experience. Plus, Mama Meisner has arguably one of the best songs in the show (Isn’t He Something?)! Also, it was the final show in the old Union Theatre before it moved over the road.

In 2015, you played Helene in Henrik Ibsen’s A Doll’s House at Barons Court Theatre, what was this like to do?

It was a real pleasure. It had a fairly small cast and the Barons Court Theatre was quite tiny, so we were spending a lot of time in very close proximity to each other. Everybody involved with the show was very talented and so much fun that it was one of those jobs that you really miss the people when it finishes.

How was your time as a vocal booth singer in the West End production of Starlight Express at the Apollo Victoria Theatre?

It was an amazing time. I depped on it, which meant that I was called in if someone was off. I have always loved Starlight Express, so it was lovely being able to sing on the show. I believe Starlight Express was the last West End show to have a vocal booth.

What was it like working on 84 Charing Cross Road as Cecily Farr?

The building at 84 Charing Cross Road was empty at the time, so we were able to perform the play in the actual place where everything took place between 1949 and 1969. It was very atmospheric and wonderful to perform there.

It is now a McDonald’s!

What are some of your favourite memories from being in the cast of Les Misérables at the Palace Theatre in the West End as Ensemble and understudy Madame Thénardier?

My first one was of the excitement I felt at being cast in it. When I first saw it in the late 1980s, it was such a groundbreaking show. The set was spectacular, and the music and performances were so moving, so to become a small part of the history of that show has been amazing. In rehearsals, stepping onto the revolve for the first time as it went round was quite daunting – but at least I didn’t fall over!

Going on as Madame Thénardier has been one of the highlights of my career. The orchestration was so beautiful, and it was such an honour to have been given that opportunity.

You were part of the Les Misérables 10th Anniversary Concert at the Royal Albert Hall in 1996 and the 25th Anniversary Concert at The O2 Arena in 2010, how did you find the experience performing in both?

They were both very exciting, but slightly different. By 2010, there had been many more performers in the show over the years, so the cast at the O2 was much larger. It was lovely working with old friends again and meeting new ones. The experience of working at two iconic venues was amazing.

Early in your career, you were in the Ensemble and understudied Sister Berthe on the UK Tour of The Sound of Music, how was it touring with the musical?

The Sound of Music has been one of my favourite films since childhood, so it was incredible to be Swing Nun for 12 nuns and understudy Sister Berthe. The tour cast were wonderful, and working with Christopher Cazenove, Liz Robertson, Robin Nedwell and Linda Hibberd was a joy. I made lifelong friends from that production, for which I am very grateful. I am currently working with Clive Marlowe again in The Mousetrap.

We understand you were one of the backing vocalists on Lesley Garrett’s Travelling Light Tour, can you tell us about this?

I was very excited to be asked to do this. It  was great fun and amazing to be singing with such a talented group of people. Lesley Garrett was lovely, and we played some wonderful venues.

How did you originally get into acting, and was it something that you wanted to do professionally?

I had sung from a very young age and always thought that that was what I might like to do as a career. Then I watched The Duchess of Duke Street on television. The cast included Christopher Cazenove, Gemma Jones and Mary Healey, and I was so mesmerised by the costumes, the script and the acting that I felt an incredibly strong urge to pursue it professionally. I did a couple of plays when I was at my local college of Further Education and then auditioned for drama school.

Is there anything that you find most rewarding about being involved with the acting industry, and can you say about some of your future acting projects?

Some of the most rewarding things about this business are being given the opportunity of inhabiting other characters and the endless possibilities of creating new worlds with other actors. One of the most heartwarming things is when audiences truly immerse themselves in the cast’s performance – hearing the audience’s reactions, from laughs to gasps and sometimes screams, to me, shows how immediate and almost visceral live performances can be.

There are a couple of things that I hope may be in the pipeline, but only time will tell.

What are some of your favourite shows to watch?

I love all theatre, whether it is Shakespeare, the classics, musicals, straight plays, or comedies, and in any type of theatre large or small. I still find it very exciting sitting there in the audience, waiting for the performance to start.

How do you like to spend your free time?

Spending time with my family and friends. I read a lot, and I have started wood whittling, but find it quite hard to find the time to do that!