Agatha Christie’s The Secret Adversary
Devonshire Park Theatre, Compton Street, Eastbourne, Tuesday, March 31, to Saturday, April 4. Starts 7.45pm, 2.30pm matinees Wed and Sat, tickets from £15.50. Call 01323 412000.

They’re not as well-known as the Mistress Of Suspense’s classic characters Hercule Poirot and Miss Marple.

But the detective team of Tommy And Tuppence – the heroes of Agatha Christie’s second crime novel – may become household names through an upcoming television drama series and a national tour of their first adventure by Watermill Theatre.

In the original novel The Secret Adversary the former friends set up their own detective agency The Young Adventurers Limited having met by chance after the First World War. They soon become embroiled in a world of intrigue, political espionage and murder with a cast of shadowy figures.

The ITV version starring Jessica Raines and David Walliams is being transposed from its original 1920s period to a 1950s setting.

“We are being more truthful to the book,” says Emerald O’Hanrahan, who is playing Tuppence, speaking from the Watermill’s base in Newbury where the touring production began life.

“A lot of our atmosphere and joy comes from the amazing noir-ish 1920s set and music which has got some real 1920s tunes. With the costumes it brings the world to life.”

She feels the period adds an edge to the central characters’ reunion following the First World War.

“They aren’t naive kids forming a detective agency,” she says. “There is an element that they want to be back in a more innocent age where they didn’t know about the horrors of war.”

The relationship between the two detectives is central to the story, and carries on through Christie’s books.

Unlike Miss Marple and Poirot, Tommy and Tuppence age through the series of four novels which also include 1941’s N Or M?, 1968’s By The Pricking Of My Thumbs and 1973’s Postern Of Fate – reputed to be the last novel Christie wrote.

“Throughout the books the detectives and Christie age together,” says O’Hanrahan. “By the time of the last novel they are in their 70s or 80s.”

O’Hanrahan and co-star Garmon Rhys as Tommy are the only two actors to solely play one part, with the rest of the story’s characters being taken on by five cast members.

“The plot [of The Secret Adversary] takes so many twists and turns their relationship is something to hold onto,” says O’Hanrahan “We have spent a lot of time in rehearsals looking at Tommy and Tuppence’s childhood and rediscovery of each other. Tommy was injured in the war, and Tuppence was a nurse at the field hospital he went to, so they have seen each other in 1916 during the horror of the war, and then realised later that they are still alive.”

Propelling the move from the page to the stage is co-adaptor and director Sarah Punshon.

“Sarah is an Agatha Christie obsessive,” says O’Hanrahan. “As a child it was always her dream project to do Tommy and Tuppence.

“It’s very different from the sitting room drama that you associate with Agatha Christie. Audiences have been saying they weren’t expecting it to be so farcical and funny.”

Throughout the run O’Hanrahan is continuing her other day job as Emma Grundy in The Archers, a role she took over from The Theory Of Everything star Felicity Jones in 2010.

“It’s my first theatre for a couple of years,” says O’Hanrahan.

“The stage is the actor’s medium, whereas telly is the editor’s and radio is the writer’s. Being on stage telling a story is so freeing and liberating.”

She was an Archers fan before joining the cast.

“Growing up with my granny I knew the show inside out,” she says.

“It’s a real honour to be part of such a British institution – The Archers is so much part of our culture and history.”

As for the future she hopes to continue to play troublesome mother-of-two Emma in between plays and screen work.

And she is particularly looking forward to coming to Eastbourne with The Secret Adversary.

“I went to Eastbourne a lot with my granny from the age of three or four,” she says.

“I have family in Hassocks too – my aunt Rachel Bor was in a band called the Dolly Mixtures and her partner is Captain Sensible. I’m hoping they will be able to come down and bring my granny along!”