The little grey cells had to work extra hard on Banbury Cross Players’ latest production due to an unforeseen and safety.

Agatha Christie’s An Unexpected Guest features copious smoking scenes. But, as director Terry Gallager explains, local authority rules allow just two herbal cigarettes to be smoked on stage per performance, sparking a rethink.

“It was a big problem – three of the main characters smoke throughout and the plot centres around collecting up the stubs. I had to carefully tweak the storyline – for example Laura [the murder suspect] becomes a heavy brandy drinker instead – we’ve definitely pushed her to the drink!”

It’s hurdles such as this – not to mention acquiring 1950s drawing room furniture on a limited budget, creating ‘fog’ and looking after two live hand-pistols on set (which are giving Terry sleepless nights) – that demonstrate just how versatile local theatre teams have to be.

No wonder ex-Army man Mr Gallger, 68, says his nerves are shredded from the 12-month stint.

“I always say ‘never again’! But I knew another Christie would be popular with the Mill audience and wanted to have a stab at it in case it was my last chance.

“Christie was primarily an author, but she was in love with the theatre. I know the thrill of staging her plays. I got stressed doing Dial M For Murder a couple of years ago, but at curtain-up it was a white-knuckle ride for the audience.”

Banbury Cross Players are plugging new talent with three actors turning in debuts, including A-Level student Cameron Anderson who plays a learning-disabled teenager and has thoroughly impressed his fellow crew, who have gelled well during rehearsals.

But with detective drama, especially Danish imports, being very much the zeitgeist, does this mean we’re all super-sleuths now? Will it be too easy to solve?

“It depends how subtle the plot is,” says Mr Gallager. “I love this play and like to think it will fox people because there are so many twists.

“I feel the thing is to grab the audience’s attention and keep hold of it.”

So picture the scene. In a darkened room, light filters in through the bay windows. There’s a squeal of brakes, flashes of torchlight and in bursts an intruder, apologising to a man in a wheelchair. This man is dead.

Silently, a woman steps forward, nursing a smoking gun. Compelling stuff.

Mr Gallager adds: “The magic of the theatre is assembling a room full of people who don’t know each other. They’re all strangers, all in the dark – hopefully we’ll take them on a journey and allow them to look into these lives like a voyeur.

“It’s hard to beat.”

An Unexpected Guest runs at The Mill Arts Centre, Spiceball Park, Banbury, until Sunday. Call 01295 279002.