I’VE been talking to Robin Wright Penn for 10 minutes and she’s already slipped into an English accent three times.

We’re in Edinburgh where she is promoting her latest film The Private Lives Of Pippa Lee and on the first two occasions I assume she’s putting it on for comic effect.

On the third, I can’t help but point out these moments of received pronunciation and she looks startled.

“I know,” the 43-year-old says confessionally. “It’s because when I’m around you people I feel just like I have to speak like this because I hate my accent. I feel very American around you guys.”

She starts making a whining sound and adds: “That’s what I sound like to myself when I’m around you.”

Robin’s father is English so she had a head start with the accent and the California-based actress admits that – after putting on her costume – adopting another accent helps her get into character.

“Clothing is so important to me when finding a character. It changes your walk, the way you hold your arms, the way you sit: it’s maybe the most important thing. Of course, if you have an accent that’s even better.”

In her title role as Pippa Lee, a 50-year-old woman heading for a mental breakdown after moving to a retirement village with her older husband, Robin didn’t have to feign an accent. But her clothes, she says, were instrumental in getting herself into the prim and proper role.

Given starched beige trousers and plain blouses, her on-screen wardrobe is eyecatching in its plainness.

“It was genius picking those very conservative wardrobe pieces for me, and the curl in the hair aged me too.”

Although close to her character in age, the actress says the clothes really helped her get into the part.

“I really felt her, every day, because I wear this,” she says, pointing at her skinny jeans and tailored leather jacket. “Always have.”