Interview: Actors Taz Skylar and Alexandra Guelff Talk WITNESS FOR THE PROSECUTION

The Agatha Christie favourite Witness for the Prosecution appears to be a jury-pleaser. Opening in 2017, it's currently booking at London's historic County Hall until September 2020 - surpassing the play's original West End run - and celebrates its 1,000th performance on Saturday.

We talk to cast members Taz Skylar and Alexandra Guelff about performing the show in such a unique venue and why Christie's work is still so popular.

To start with, I presume you are innocent and haven't been involved in an elaborate murder mystery yourself?

Taz: Funny you say that ... [laughs]

Alex: Please state for the record that I haven't been to court for murder... but I have been as a witness. Even when you're a witness, you feel a bit guilty - there is just something so imposing with authority in an institutional set-up.

Why do you think Agatha Christie is still so popular?

Taz: I think Christie's work, in general, is timeless. She is to murder mystery what Shakespeare is to verse and sonnet. No matter how much someone tries to redo the murder mystery genre, there is always an element of Christie in there. Her stories are the purist version of murder mystery - the structures she put in place to tell those stories are so brilliant and dexterous that you can't redo them without her essence in them.

Alex: I think she is very satisfying entertainment. It's so clever but not alienating, it's accessible to everyone, it's witty and intriguing and playful and so funny - you don't expect to have as many laughs in a murder trial as this gets.

There is so much that is current and relevant about our plot. There is so much to say about the political climate of today and how we form judgments of people, and Christie unpicks it and leaves it in front of you.

There are many TV and film adaptions of Christie's work - do you feel her stories are captured better on stage or screen?

Taz: I feel sometimes in film, plots can be so complex that you lose an element of simplicity and the audience find it hard to understand. Her stories are real and cathartic and keep you gripped; they can keep you guessing, but also allow you enough information to be hooked and keep going with the story. You feel smart while you watch it - Knives Out is a great example of that. It goes back to the essence and is a cathartic experience for the audience.

Alex: I'm a theatre baby through and through, and my character has such a tremendous arc during the play - you see so many sides of her. If you were to do all of that in isolation, as you would do in filming, it would make it not feel like one human being. When you can run through all of those things in two hours, you get the visceral thread that runs through her and she starts to feel like a very detailed woman.

Taz: On the West End and off West End, you can get access to characters that are so dexterous and interesting and complex that I wouldn't necessarily get access to in TV and film. Ben Affleck is doing a version of Witness for the Prosecution, and you can bet that the actor playing Leonard Vole will have a vast CV behind him, which will make him an attraction to the film.

With the play, you're not attracting a million people per night, the pressure isn't is on; they rely more on Christie's work and finding actors who can portray the roles. It gives me access to play a character I wouldn't usually play. I usually I get characters you can define in one line - 'the boyfriend of the lead', for instance, where Leonard is a lot more difficult to define and I love getting to work on such a character.

Alex: I think part of the reason the show is popular with tourists in particular is because of the TV and film versions of Agatha Christie's stories having more of an international reach - she is one of the most widely published authors in the world. We also get a real die-hard English following with the show, as she has such a huge fanbase here.

The set is truly unique, with the audience sat into a courtroom. Does that help you to embody your character, and does it add to the audience experience?

Taz: I think theatre is a cool thing and I hope theatre becomes cooler; it's such a breeding ground for culture. For that to happen, theatre has to evolve with the culture and population, the same way that film does, and I think setting our play in a place like this is a great step in evolving culture. You step into a place that immediately makes you feel connected to the story and the characters in it.

It's not immersive in that actors run around you, but you feel like you are part of it. At any given moment, an audience member can be as well-lit as an actor ,or at any moment an actor can clock eyes with a member of the audience.

Alex: It helps enormously. It feels more like we're on a film set instead of in a theatre. Instead of the whole world of the play being what the audience is looking at - and as an actor, you would typically see red velvet seats - everything you look at in this production is that of the real world of the play, and the audience reactions contribute to the real world of the play... It's amazing!

There is no fourth wall - you are all in it together. And lucky for the audience, they are in big comfortable seats that lots of powerful men have sat in before them. It's like no other experience I've ever had.

In such close proximity to the audience, has anyone's reaction ever caught you off guard, or has anything gone wrong and an audience member spotted it?

Taz: Theatre is theatre, so every night is different. The turnout is great - more often than not, the audience is at 90% to sold out. The whole team is doing wonders at selling the show; it's such a testament to the creative team, marketing team, and the cast.

With doing the show every day, sometimes things go wrong and I love that. If something goes wrong everyone has to figure it out live on stage, and because you're doing it so much you often find times that you are so comfortable in the skin of the character you say or do something you have never done before.

Alex: Twelve audience seats are in the jury box itself, so when you're in the witness box, you are testifying to those audience members. It's amazing to be testifying and looking at people and seeing how transparent their thoughts are. People forget they are at the theatre and take it seriously at times.

I've been called a number of rude words. In December I was hissed at a lot, and I almost broke character to assure them that this wasn't panto. There was one man the other day who, after I said one my wittier lines, audibly said "Jesus Christ"...

Witness for the Prosecution is at London County Hall until 13 September