I’ve never seen an episode of Keeping Up With the Kardashians but I’m told it’s the living embodiment of empty celebrity. Something of that world is explored in Adam Bock’s black comedy The Colby Sisters of Pittsburgh, Pensylvania, about a quintet of glamorous, wealthy but faded It girls on New York’s social scene.

The sisters appear to have it all – money, status and desirable husbands. But keeping up the perfect image amid vicious behind-the-scenes squabbling is a struggle that threatens to bring them down.

British actress Claire Forlani, whose career to date has been entirely on screen, knows a thing or two about celebrity la-la land, having spent two decades acting in American films and TV.

The 42-year-old, whose work ranges from NCIS to movies opposite Brad Pitt and Nicholas Cage, moved to California aged 19 with her family and built a career.

“It’s challenging. I haven’t done a play since school, but I had wanted to do one for a long time and for me it’s the technical side of acting without a camera.

“The rehearsals are so high intensity compared to film or TV, where you have a couple of scenes a day to focus on and you can do retakes and save yourself for the moment on camera.

“Here you are doing all the scenes going full tilt at your full character arc, every day, all day long, then you go home and figure out how to make it better. There is no emotional reservoir, that’s why theatre actors have such ability, technique and stamina.”

If stage is bigger and film smaller, Forlani is enjoying “letting it all out”.

“I keep saying, ‘I think I went really big there,’ she laughs.

“I’m amazed how much I am learning, but also how much acting is just acting. Preparing a role is the same.”

Dynamics

Forlani, who has now returned to the UK with her actor husband Dougray Scott, plays the eldest sister Willow.

“It’s about the dynamics between the sisters and their different journeys when a major life-changing event ocurs, how we all evolve, how she has to find the strength to get back to being the protector for her sisters.

“It feels farce-like but there are darker undertones. You think it’s one thing, then it becomes another, more interesting play.”

“Willow’s a bit of a lunatic, a roller coaster of a human being. In a weird way it’s fun being allowed to be this emotional because my character is this way and I am not going to be judged for it.

“For a guy to have written these five women is incredible. He understands the nuances of the sisters’ dynamic and the female condition, how emotions change with the hormonal changes throughout the month. Being allowed to explore that, not being afraid to go balls out with it, has been great.”

If the sisters are fighting on-stage, it’s been love peace and harmony off-stage for the six actresses.

“There’s something wonderfully relaxing about getting to work with six women, no men. They are great girls, so sweet, and I’ve been really happy being allowed to do a story where each is a strong female character.”

Does that mean she found a lack of strong women in her screen work?

“The good thing about doing film and TV for 20 years is it’s evolved and I play completely different characters now to 10 years ago.

“The beauty of acting is the roles forever change. I used to be the ingénue, the girlfriend, then wife, mother, look! now I am a queen, the crazy journey of this business is always exciting.”

Asked whether she plans more stage work or a return to TV and screen, Forlani replies:

“I am an actor, so I am imagining I will do all three, but maybe I will never be allowed to go on stage again after this.”

Bridget Galton

The Colby Sisters runs at the Tricycle Theatre from June 25 until July 16. Box office: 020 7328 1000, tricycle.co.uk.