Kristin Scott Thomas‘s first foray into directing is surprisingly personal.

“It was about about six, seven years ago,” the British star of screen and stage tells The Hollywood Reporter about the origins of her upcoming film. “I realized that my brothers had absolutely no recollection of their father.”

Scott Thomas, the eldest of five children, found herself wanting to make something for her siblings. Her father, an English Royal Navy pilot, died in a flying accident when she was just five. Her mother remarried and had more children with another Navy man, who also passed away in a similar tragedy when Scott Thomas was 11. She used to turn her memories of these two father figures into animated films for her brothers and sisters, but one day, someone suggested she make a feature film instead.

“I’ve been curious about it for a very long time,” Scott Thomas, best known for her roles in Four Weddings and a Funeral, The English Patient, and more recently, Fleabag and Slow Horses, says about sitting in the director’s chair. “I find it very difficult to actually get my head around the fact that I made the decisions. That was really hard for me, because for so long I’ve been in the position where I am being driven rather than driving.”

Scott Thomas takes to the driver’s seat with confidence in Vertical’s My Mother’s Wedding (formerly titled North Star) set to hit U.S. theaters on Aug. 8 after its 2023 TIFF debut, with Scarlett Johansson, Sienna Miller and Emily Beecham. The three women play sisters Katherine (Johansson), a Royal Navy captain, Victoria (Miller), a celebrated actress and Georgina (Beecham), a palliative care nurse. They reunite in the English countryside for the third wedding of their twice-widowed mother, Diana (played by Scott Thomas).

Diana’s first husband was a Navy pilot who died shortly after Victoria’s birth, and his best friend, who then became Georgina’s biological father, also passed away when the girls were young. If it sounds familiar, Scott Thomas is glad. In My Mother’s Wedding, she takes an intimate, often autobiographical look at motherhood. The women battle “disastrous” romantic lives and raising children with an enduring sadness for the men they never truly knew, all while their eccentric mother is getting hitched.

Below, Scott Thomas talks to THR about making My Mother’s Wedding and what’s in store next. She discusses casting the “little gaggle of women” — Johansson, Miller and Beecham — and what she found particularly difficult about directing her first film: “That was a difficult corner for me to turn — to stop being apologetic. ‘I’m really sorry I’m asking you to do this.’ No, they’ve agreed. They’ve turned up. They’re happy.”

Kristin, when did this journey start for you?

It was about about six, seven years ago. I realized that my brothers had absolutely no recollection of their father. My brothers are from different fathers, so I’ve got one brother who has the same father as me, but he was born after our father died, and my stepfather had a child with my mother and then, of course, he died. So I have two brothers who have absolutely no recollection — and actually, my sister [too] because she was only a baby. Nothing to hang their hat on. Yet it’s half their DNA, it’s really kind of a big deal.

I was the eldest child of five. I would put down my memories and make them animated films. I’ve always loved animated film. And I’d give them to my brothers and sisters [and say], “This is what happened. This is what [he] was like.” Of course, everybody’s memory is different… But my memory is the correct memory, because I was almost six when my dad died and 11 when my stepdad died. So anyway, [the film] started like that. I wanted to do this as a personal project. And then someone said, “Well, it’s really interesting, how did that affect your life?” And they said, “You should make this into a feature film.”

And that’s how My Mother’s Wedding was born?

Well, I said, “Yeah, but I don’t want to do a feature film that is all doom and gloom and misery.” Because if you ask me or any of my siblings whether they had a happy childhood, they say yes. People say children are so resilient. They are to a degree, but they will go with the flow. But on the other hand, if you don’t deal with these huge events in a child’s life, if you don’t somehow get them out in the open, then they can turn against you. And like Katherine in the film, she’s just become so driven and so obsessed. She hangs on to these memories as if they were her life jacket, and she can’t survive without them. Which is why they’re all so upset when their mother remarries.

And you have two sisters — were these three central characters loosely based on you? Are you Katherine?

I think there’s some of me in every single character. When you’re writing fiction based around autobiography, there’s got to be stuff that comes in. I think everybody, when they’re creating characters, there’ll be something in there that they can recognize. I’m very different from Katherine, I’m very different from Victoria, and I’m very different from Georgina. You could say that Katherine is career-driven — well, I’ve been career-driven. Victoria is is an actress, I’m an actress. Georgina is a homemaker, and I’m a homemaker. So quite a lot of women are in that situation. I mean, the one thing that [I am] similar [in regards to Katherine] is that I am the eldest and always being accused of being bossy.

There’s a lot going on — lost fathers, Georgina’s marriage is in jeopardy. Victoria is dealing with her own demons, and Katherine is struggling to balance her own marriage with bringing up children and being away for work. What exactly were you trying to spotlight, or is it just an exploration of womanhood in general?

It’s an exploration of motherhood, really, because all of them are mothers, and they’re all trying to have a romantic life as well as being a mother. How does that all work together? Sometimes I explain the film by saying, “You’ve got three daughters going home to their mother’s third wedding, and the daughters are romantically disastrous and their mother is deliriously happy and they’re furious about it.” It’s the passing of the baton between being a daughter to being a woman. And that’s what she says in her speech, [Scott Thomas’ character] says, “I brought you up not to be daughters, but women.” It’s a film about getting real and not living in a fantasy world of, “Poor me.”

I’m exploring children, sisters, interactions. To be an adult daughter with a mother is very different from being a child with her mother. I’m exploring the feeling of responsibility towards your children. Katherine is such a detached mother. Her son even calls her Katherine. It’s a very hands-off approach, and she feels guilty about that, even though there’s nothing to be guilty about.

What was it like co-writing the script with your husband of one year [Bloomberg News editor-in-chief John Micklethwait]?

My fresh new hubby. [Laughs.] He really encouraged me, and then I said, “I can’t do it by myself.” And he said, “Well I’ll help you.” He has an enormous amount of experience in newspaper editing, he’s quite good on plot and how to make things go from A to B, narrative. I’m much better on dialogue and the way characters interact. So we work quite well together.

How was it sitting in the director’s chair? Is this something you’ve always wanted to do?

I’ve been curious about it for a very long time. I’ve worked with a lot of directors who were actors at some point, and that is always really interesting for me, an actress, because they see both sides. They see what it’s like to be in front of the camera, and they see what it’s like to be behind the camera, the prepping. I find it very difficult to actually get my head around the fact that I made the decisions. That was really hard for me, because for so long, I’ve been in the position where I am being driven rather than driving. That was quite hard.

I’m completely in my element when I’m on a film set. I’ve been doing it for such a long time I’ve practically grown my own battery pack in the back of my skirt. Scarlett and Sienna were both child actors, they were all very comfortable on that set. We just became this little gaggle of women, lots of them seemed to be nursing babies at the same time, which caused quite a headache for the first AD. We constructed a very affectionate, freewheeling film set. It was a very happy film set. I managed to do a few things like keep everything very local, so there wasn’t much traveling in the mornings and things like that. It’s all the things that you find out being an actress, the stuff that’s really tricky. We shot the naval ship first. Suddenly, we were on this ship and I was feeling incredibly apologetic for making everybody wait in the car. That was a difficult corner for me to turn — to stop being apologetic. “I’m really sorry I’m asking you to do this.” No, they’ve agreed. They’ve turned up. They’re happy.

What a baptism of fire, filming on that ship.

Yeah. And we were so well looked after by the Navy. They pulled out all the stops, and they were amazing. I have an affection for being on those ships, because it really takes me back to my childhood.

I was going to ask about that element, how you honored military work. That must have been a particularly personal intention.

Yeah. I’m talking about a parent’s commitment to a career. It can be a bit perplexing for a child, but when you go onto a ship and you see your dad with all his uniform on looking like Prince Charming, you learn to think, “Oh, that’s really big.” You go onto a ship, the size of the thing is so enormous. It really dwarfs you. So you feel that what they’re doing is really, really, really important, which I think perhaps a lot of kids don’t have because they see their dad going into an office or going into a factory or getting on a tractor.

It’s fascinating that you shot that scene first, because the chemistry between you all was so great. Scarlett, Sienna and Emily so convincingly portray sisters. I know you’ve played Scarlett’s mother twice before [in The Other Boleyn Girl and The Horse Whisperer]. How much say did you have over casting, and why was everyone so right for each role?

Oh, thank you, because we had a very good casting director called Lucy Bevan. But the role of Victoria, I’d only ever met Sienna once, very briefly, in passing. I’d seen her be really funny once, and I thought she’s a brilliant actress. She’s so good, and she’s so beautiful, and she will just understand this character. So I sort of wrote it for her, always thinking about her.

It took us quite a long time to find the right person to play Katherine and so with Scarlett, I just rang her up. I had a very short window, because I was doing Slow Horses, and I knew she had a very short window. So I said, and I’m terrible about this — people send me scripts and then weeks go by and it’s still sitting there, looking at you reproachfully, saying, “Read me! Read me!” — I said to Scarlett, “Please can you read this really quickly and let me know yay or nay?” And she rang me back the next day and said, “Yeah, I really want to do it.” And after that, everything just went tick, tick, tick, and fell into place. It was incredible.

I was impressed by her British accent.

Oh, good. It’s a very British film, so it was quite a brave move.

Was it weird directing a project that you’re also starring in?

It was so hard. I never want to do that again! It’s just so difficult giving other actors what they need, and at the same time, observing them.

My Mother’s Wedding is finally set to make its U.S. debut on Friday. How are you feeling about that?

I’m really excited about it, because I think it’s a great time to be able to go and see it. You can’t help coming out of that with a smile on your face. There’s something about that song at the end, that great swooping movement… It’s something about seeing the light through the clouds, about being able to get through really bad moments. It’ll be all right in the end — that, I think, is a really lovely, reassuring thing to see, especially at the moment.

It’s funny at times, moving at times. It’s quite naughty at times. It’s a very sweet tale of a family coming to terms with unexamined trauma.

I know you’ve got Slow Horses which is proving to be almost genre-defining television. Are you comfortable in TV or do you want to get back in the director’s chair?

Well, it’s funny. I know [Slow Horses] is television, but it doesn’t feel like television… It is a very, very, very, big thing — lots of people involved and very, very, very high quality. I really do think it’s one of the best if not the best. It seems a bit difficult to say [it is] the best television there is out there, because I’m in it. But I really do think it’s just so beautifully made. I’m really proud to be in it, to belong to it. And I love watching it. I’ve always forgotten the plot and [when] I watch it, I’m just as gripped as you are, as the next door neighbors [are].

The quality is so much more luxurious than half the films I’ve made, because I’ve made a lot of films in France where it really is 38 people, including the cast and everything. It’s really tiny. And I really, really love that. In fact, I’m gonna do another one in September — a film, I’m acting. It’s a French comedy about a family and I play the matriarch. I would love to do some more directing and I’ve got a plan for that. I’m going to do some stage work, so I’m going to be quite busy the next few years.

What can you tell us about your next directing job?

[Smiles]. There’s nothing to say at the moment…

My Mother’s Wedding is in U.S. theaters Friday, Aug. 8.