LORRAINE McIntosh isn’t usually lost for words.

We’ve all seen her perform effortlessly the long soliloquies required in stage plays such as Men Should Weep.

And we’ve heard her speak eloquently on Radio Four chat shows such as My Life In Five Songs, or in interviews featuring her role in Deacon Blue.

But in conversation at the Tron Theatre bar, where she’s in rehearsals for the Scottish premiere of Abi Morgan’s play The Mistress Contract, the McIntosh mouth isn’t processing thought at the normal rate.

Why? Well here’s a clue. The play tells the real life tale of a couple (named He and She in the play) who first met at university but 20 years on meet again and begin an affair.

However this highly educated, intelligent woman with a history of involvement in the feminist movement asks her wealthy lover to sign a contract.

The contract demands that if She provides companionship and sex, then He provides her with a home and material benefits.

This premise for Morgan’s play (whose credits include The Iron Lady starring Meryl Streep) however throws up a range of tricksy questions for the modern day feminist.

Can a mistress be a feminist? Is a woman who forms a relationship with a married man subjugating herself to that man by accepting the secondary relationship role? And is this contract a betrayal of all that she and the women of her generation had fought for?

McIntosh, who stars alongside Cal Macaninch in the play, smiles as she deliberates. “I don’t know,” she says after a few seconds. “I think the term ‘Mistress’ is very loaded.”

What does that mean, Lorraine? Can you say The Mistress has made the right choices?

“Well, it’s a very complex issue. I suppose ‘I’m not sure’ is the answer I have to give. I do feel though that when deception is involved, well, that’s not good for any relationship.”

There is the question of how society judges “the other woman”. The watching world hasn’t been too kind, for example, to famous second choices, from Anne Boleyn to Monica Lewinsky, to Camilla, Duchess of Cornwall. “What I do find interesting is that it’s always the woman under discussion when we talk about affairs,” says the actress. “We don’t seem to talk about the man.”

That’s valid; the single man who has the affair with the married woman isn’t labelled with what is seen to be a pejorative term. “I don’t think there is a level playing field. And in the play what is revealed is that the woman is broke. She is also trying to make sense of her life.”

McIntosh adds; “If you look at the stats in Scotland today 75 per cent of those in poverty wages are women. There is a huge inequality. Women suffer in lots of ways. So in this situation I can feel sympathy with the woman’s desire to survive. And we learn, she has been in a relationship before where all she’s been left with are ‘a couch and cutlery’.”

There are other issues raised by the premise of a play. Sometimes a mistress feels she is helping her lover’s marriage along, by providing an alternative. Sometimes mistresses have no desire to be in love, or to be looking for a full-time commitment. They can often separate sex and love. And a married man ticks their boxes.

But is She letting down all the women of the world by becoming an Occasional? “I think a play like this certainly causes us to think about that argument,” says McIntosh, who married Deacon Blue frontman Ricky Ross in 1990.

“I like the fact it talks about a vulnerable woman who feels she gains control by setting up this contract. She says if you give me certain things I will offer you companionship and sex. But this contract raises all sorts of questions; they ask if sex is simply a transaction, can it be monetised?”

McIntosh doesn’t have the answers. “But we’re having a conversation about it, which is great.”

McIntosh is aware the subject is a minefield. She’s acutely aware that comments can be taken out of context on social media. “That’s so true,” she says, smiling. “We need to learn to respect each other. We have to listen to opposing views.”

The Mistress Contract will certainly offer opportunity for debate. “Oh, yes,” she says, grinning. “Lots.”

The Mistress Contract, The Tron Theatre, Glasgow, May 1 – 11.