Kiri: Lia Williams on the distressing bathroom scene in episode three and why she doesn’t agree with the backlash from social workers

The scene in question saw Alice's son, Si, walk in on her while she was in the shower. Perturbed and embarrassed, Alice asked him to leave but Si refused and instead proceeded to tell her about a girl he had "touched" at his school. Si then changed tack and confronted his mother about her affair, asking: "Are you that desperate to be f***ed?" He then ripped her towel off her, before apologising and storming out.

We caught up with Williams to hear about filming the scene - and winding down with a very large G&T…

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What was it like to film the bathroom scene?

It was a very difficult scene to do but it's so intelligently done and I trusted everyone around me so much. We had an incredibly brilliant and sensitive director [Euros Lyn] who we knew would do it tastefully.

The most exciting thing about playing Alice is that she's such a complicated woman. The slightly oedipal relationship with her son is Jack Thorne being really interesting and brave as a writer.

What did you think when you first read that scene in the script?

I just thought it was a really great scene because it's so alarming. It's one of the things that made me want to do it. I didn't shy away from it at all, quite the opposite.

How many takes did you do it in? I imagine it's not the kind of scene you'd want to do over and over again…

I think it took about four hours or half a day or something like that, it took its time, yes. It was chilly!

How did you wind down afterwards? Warm clothes and a cup of tea?

Warm clothes and a large gin, more like! Finn and I had a drink together in the hotel we were all staying in afterwards. We get on like a house on fire.

Were you reluctant about the nudity?

I'm never reluctant about nudity in its right context and if it's tastefully done, with intention. It made sense within the story and there's nothing strange and unnecessarily voyeuristic about it.

I think it's really exciting to play a woman of a certain age where the writer can write scenes like that for her and give her a younger lover and a complex marriage and the fostering of a child, give her all these complicated layers.

Much like Apple Tree Yard achieved with Emily Watson last year, Kiri portrays Alice Warner as an older woman who has sexual presence and charisma.

I think it's good when older women are complex and sexy and interesting characters, with interesting emotional lives. They write like that all the time in French film and they write interesting psychology in American TV series, but over here we're often plot driven, and so Jack is really tapping into something exciting to write a role like that.

Episode three is all about Alice and her story, what do you hope people's reaction will be?

The really great thing is that Jack doesn't tell the audience what to think and feel. I'm hoping people will be pushed and pulled by the dilemma and by how Alice reacts to it. I hope they'll be all over the place with it because they just won't quite know.

Alice has got a lot of bad stuff as well as a lot of good stuff. She's nine miles of bad road really but you care for her anyway. That's the hope.

What do you think of the backlash from some social workers against Kiri, who say the drama depicts the profession in a poor light?

I don't have a great deal of sympathy with people who have lashed out at it. Kiri is not about categories of people, it's about a woman who happens to be a social worker. It's not even remotely making comments on social workers.

Miriam just happens to be a social worker and actually she's brilliant at her job. The fact that she's flawed is entirely human.

I do think social work is an incredibly difficult area because it doesn't deal with black and white, it deals with grey. Every family situation is different from the last and it's a very, very difficult job to do. There's a lot of flack around it and criticism so you can understand the sensitivity, but Jack isn’t writing comment on social workers. That's not what the programme is about.

He's just representing a human dilemma, wrapped up in some issues. I've only ever seen Miriam as a profoundly moving human being who's doing her best.

You’re very busy with the play Mary Stuart at the Duke of York’s at the moment, what are your plans for after that?

I'm trying to develop an independent film, because I've started directing in the last few years. We're still short of money but the cogs are turning and it would be a project of the heart. It's a fictional film, a love story, it's wonderful.

And I hope to do more of The Crown [as Wallis Simpson] but you never know... I've got my fingers crossed.