Di And Viv And Rose...and Polly too in Amelia Bullmore premiere at Stephen Joseph Theatre

No sooner was the fire finally extinguished after her electric spark of a performance as the loud-mouthed, heavy-drinking, emotionally damaged Mari Hoff in Jim Cartwright's The Rise And Fall Of Little Voice than she is back on The Round stage as the sporty, no-nonsense, lesbian Di in Amelia Bullmore's Di And Viv And Rose until August 26.

"She's crazy, isn't she!" says Polly, reflecting on playing Mari Hoff. "But I have empathy with her. That speech at the end, talking to her daughter LV, I really believe she's a woman who has so much energy, so much to give, if she'd had good parenting, a good marriage or given birth to a daughter who loved her, she would have been fulfilled, but she's had it tough."

Di has plenty of energy too in Di And Viv And Rose, but channelled into her sporting endeavours in her student days at a northern red-brick university in a humorous, poignant play that spans October 1983 to August 2010.

Polly had not seen Bullmore's drama in its Hampstead Theatre or West End runs before landing her role in the regional premiere in Scarborough. "But I was told about it when I was playing the Snow Queen at the Old Vic and a lot of girls in the cast were talking about it." she says. "I read it, but thought I might be too old to do the play at 42, but Di is in her forties at the end, so that was fine.

"I love Di; she's really optimistic, her glass is always half full, and the friendships in the play are written with such heart. They're women who you see warts and all, whose friendship from student days onwards is put under a lot of stress as a lot is thrown at them."

"Great truths are learned by looking within and that's better done if you can do it with your friends," says Polly Lister

The play's first half focuses on Di, Viv and Rose's three years at university. "That's the age when you're really trying to discover yourself, to find out who you are, to find your identity, so they're a very 'concentrated cordial' version of themselves, and then you see how life dilutes them."

Polly loves the play's candour. "These women talk and no subject is off limits," she says. "I know there's this stereotype that women slag off men and slag off other women, but what makes these three women so strong is that each is self-critical and they help each other through life's path," she says. "Great truths are learned by looking within and that's better done if you can do it with your friends.

"The fundamental thing that doesn't change in life is how you're predisposed to react to things; that doesn't change through more than 30 years in the play, when they're all thrown curveballs that could annihilate them."

Polly has enjoyed bringing Bullmore's words to life on stage. "Good writing means that the action is a step ahead of the audience, so you're taken by surprise by what happens," she says. "You have these characters where you think, 'oh, they're not going to be able to cope with that', so there's real jeopardy in this play.

"Amelia writes with huge generosity for the human spirit; she writes about people's flaws with such grace and warmth and humility, so that even when they're behaving really badly, there's real empathy."

Di And Viv And Rose runs in The Round, Stephen Joseph Theatre, Scarborough, until August 26. Box office: 01723 370541 or at sjt.uk.com