Morven Christie and Vicky McClure drama The Replacement mines the full horror of… maternity leave

Morven Christie's Ellen, happily married to psychiatrist Ian (Richard Rankin), is due to go on maternity leave after unexpectedly becoming pregnant and Paula (Vicky McClure) will be filling in for her as a senior architect at a blue chip firm based in Glasgow. All seems innocent enough. At first, anyway.

During her interview for the job, Ellen spotted something about Paula and pushed her to the fore despite doubts expressed by her senior colleagues about Paula’s lack of experience and the fact that she has taken a lot of time off.

She just seems to have something, Ellen maintains. Quite what that something is will no doubt be painfully unpeeled over the course of this gripping three-part drama.

Paula seems far too keen on getting to grips with Ellen’s big project – a new library that has earned the company a large fee, lots of kudos and seen Ellen promoted just as she is forced to take time off.

Paula's enthusiasm to get back into work – she had taken a long time out to look after her own daughter – begins to seem like pushiness... and then something else altogether.

Ellen and Paula work together for a few weeks, but during this overlap Ellen finds that she is cut out of meetings and finally is manoeuvred into doing something really serious (and a bit stupid) that gets her into a lot of trouble.

I liked the idea and the setting. The Replacement is an interesting look at the modern workplace, a story of professional rivalry with hints of classic films like The Hand that Rocks the Cradle and Single White Female.

Yet the story of two women at odds at work and starting to hate each other never lapses into cliche. It is dramatised with care and discrimination – the writing and the performances remains very alive to the force and power of small things, stray looks often conveying a great deal.

For Ahearne it is not a story of two women, as such, but of various people's struggles with identity.

“You’ve got one woman who wants to get back to work more or less straight away and you’ve got another woman who has worked part time and taken a lot of time away and when you’ve got those two people across a table, they’re gonna upset each other,” he says.

“You’ve got two women who’ve made very different life choices and the life choices they’ve made challenge each other and that's where a lot of the energy comes from. The fact that there is a maternity leave means it involves women because only they can fall pregnant. But it is not about them 'being' women."

The co-stars also pooh pooh the idea that there is anything particularly feminine about their characters' dynamic – or their rows.

“Men fall out as much as women fall out," says McClure. "Some of the dramas I hear from men... it’s the same. It doesn’t matter. You have dramas within your family, with your mates, with your girlfriends. If ever you fall out with your girlfriends, sometimes it can be quite dramatic... especially if you’re drunk, if that’s all going on. Yes, women can be bitchy, but so can men."

For Christie (below) the particular frisson attached to rivalry between women dates back to brutal historic sexism. “I think probably it hangs about because we used to burn women at the stake for being witches,” she says.

As for where the drama will take us, McClure wont give anything away but she insists that there was much she sympathised with about Paula; McClure is an actress who has a commendable habit of bringing a natural sensitivity to every role she plays and she does so again here, despite admitting to her character's very dark side.

“I think a lot of characters that I’ve played, you’re sort of thrown into the deep end and you think, they’ve got a bad side, but there’s a reason for [the way Paula is]. But don’t get me wrong, she’s twisted. She’s a hairy spider.”

Just how hairy and twisted, only time will tell….

The Replacement starts on BBC1 on Tuesday 28th February at 9pm