This year marks the 60th anniversary of the Disney classic The Parent Trap, first released on June 21st, 1961 and now available to stream on Disney+. In the film, teenage twin sisters, Susan and Sharon (both played by Hayley Mills, who was 15 when the film was released) swap places as part of a scheme to reunite their divorced parents and get up to all sorts of trouble as they carry out their mischievous plan.

During this 1-on-1 interview with Collider, Mills talked about growing up surrounded by the entertainment industry, as the daughter of the great actor Sir John Mills and the well-known novelist and playwright Mary Hayley Bell, started her acting career at the age of 12, what it was like to get the call that Walt Disney wanted to meet her, the experience of spending time with him at Disneyland, the unusual challenge of playing twins in The Parent Trap, how different it was to make the 1980s sitcom Good Morning, Miss Bliss, and her upcoming memoir, Forever Young.

Collider: The movies that I grew up watching the most were Parent Trap, Freaky Friday and Bedknobs and Broomsticks, so it’s very cool to get the chance to chat with a real Disney legend. When you began your acting career, was it something that you chose for yourself? Was it something you’d been wanting to do or was it something you found yourself in before you realized that you wanted to do it?

HAYLEY MILLS: It started when I was 12 and I was always acting, in my own life. I was always being people and pretending to be somebody, all day. My father was an actor. My mother had been an actress and she was a writer. I used to go to the studios where he was working. I used to go to theaters where he was rehearsing. It was all around me. And when the opportunity to do my first film came along, which was Tiger Bay, because of my experience with the family, it just seemed like the most normal thing to do. Of course, I was thrilled. I wanted to do it. But I just fell into it, really. It got more difficult when I got older and I realized there was a bit more to this acting business then I had thought.

When you got the call that Walt Disney wanted to meet you, was that a big deal at the time? What did that mean then?

MILLS: Walt Disney was very famous, of course. The first film that I’d ever seen was Bambi. And then, it was Snow White and the Seven Dwarfs, which I had nightmares about. Walt Disney was a name I knew. When I was going to see him in London at the Dorchester Hotel, I went with my parents and my younger brother, Jonathan, and my parents were so excited. That added to the whole thing. But he was so normal and sweet and lovely and unassuming. He was just a guy in a yellow cardigan, and he was really friendly to me and my brother, Johnny. It didn’t feel like an audition. He wanted to see me about Pollyanna, but I don’t remember him talking about it even. It was very, very relaxed. I was extremely lucky because my father was a big star and my mother was a very vivacious, lovely, witty woman and a very good writer and, and they were great company. They got on very well. Walt Disney liked them very much. It wasn’t like an audition. He talked to me and gave me a Coca Cola, but then he chatted with my parents. I was just there, being a child.

I love seeing the old footage of you at Disneyland with your parents and with Walt Disney. What do you remember about being at Disneyland, especially in the early years of the theme park?

MILLS: It was Walt’s favorite place. We stayed there overnight, and he drove us there. He went on every ride with us. He walked everywhere, and they didn’t mob him. It was interesting, they recognized him, they were thrilled to see him, and they were delighted, but they didn’t mob him. He even went on the cup and saucer ride, which makes every grownup throw up. He loved it. It brought out the big kid in him.

You got to do something in Parent Trap that not a lot of actors get to do, which is playing twins. What was that experience like, as an actor? Were there challenges specific to that, especially doing that at that time?

MILLS: Yes, it was challenging, but it was great fun as well. Great credit goes to the director, David Swift, because he kept it fun and he didn’t let me see the sweat and the stress, if we were running over or anything like that. I had a photographic double called Susan Henning, and she was a very nice, sweet girl. We had fun together. She was also an actress. It was split-screen in its infancy. There were very few films that had been done like that. It was quite basic, but it was very effective. I would play one side of the screen as say Susan, and then go and change my clothes and play the scene with my double as Sharon. It was actually very confusing, at times. When Sharon was pretending to be Susan, and Susan was pretending to be Sharon, I couldn’t quite remember whose voice I was supposed to have and what accent I was supposed to have, so the accent wavered a little bit. I think that really worked in my favor because people could say, “Well, she doesn’t have a very good American accent, but that’s because she’s Susan playing Sharon.” It was a long shoot. It was four months with wonderful actors like Brian Keith and Maureen O’Hara – people that had done fantastic movies. Working with those people, you just feel that you’re along for the ride because they really know what they’re doing. It takes a sense of the responsibility off. Obviously, I had the responsibility to do a good job and do the best I could, but I never felt I was carrying a film, or anything like that, because I wasn’t.

Parent Trap also gave you the opportunity to become a recording artist with a hit record.

MILLS: Yes, that’s true. That’s right. Who would have thought that song, “Let’s Get Together,” would be such a success. The Sherman brothers wrote it and I remember the first time they played it to me. They sang it together and they made all these terrible faces, and we all thought it was terribly funny. It was a gimmick, really. It was a gimmick song. It just shows what a good sense of humor the public has because they enjoyed it. It did well, actually. It got in the Top 10.

You also did the TV show Good Morning, Miss Bliss. After that show was canceled, were you surprised to find out that it would get a new life in syndication as flashback episodes of Saved by the Bell?

MILLS: No. I thought, “Well, that’s just the way it goes.”

What do you remember about working with that group of actors?

MILLS: Oh, they were great. They were really great kids. I loved them all. It was a different kind of working experience. I’d never done a sitcom like that, with last-minute scripts. When you’re working on a feature like the Parent Trap, the script that was written by David Swift was honed to perfection, with the comedy and the timing and the character development, and you had time to study and learn it. When you’re doing a sitcom, you’re given new pages right up to the last minute, which can produce some good spontaneous work, but it can also trip you up because you’re not quite sure about where you’re going.

You have your memoir, Forever Young, coming out in September. Was it hard to open up about everything, or is it cathartic to do something like that? When you’re reflecting on your life in that way, does it make you look at anything differently?

MILLS: Yes, it does, absolutely. It really does. It’s such a wonderful opportunity to go back, revisit it, and try to get inside your mind and how you were, what you thought, and what you felt about things, at that time. It was a wonderful opportunity to do that. I was prompted to do that by my son, Crispian, who’s a screenwriter and a musician. He helped me tremendously. I found that it was very easy to go wandering off and end up in a swamp that I was fighting to get out of. The discipline of writing, I enjoyed. I don’t think I’m a very disciplined person. I am when I’m working, when I’m filming, but this was something quite different, being on your own, day after day after day after day. But that was also helpful because we were in lockdown. I wrote the book throughout the last 15 months. We couldn’t go anywhere or do anything anyway, so it was good. It kept me off the streets.

The Parent Trap is available to stream on Disney+.