“I was always very pro the Durlseys, I liked who they were, because they’re just trying to do well in life. I think a lot of children have that experience of their parents who they find boring, old-fashioned, nerdy. Actually the poor old Dursleys were just trying to get on with it.”

She does, however, acknowledge that Vernon and Petunia weren’t without their faults.

“Maybe they were slightly trying to top their neighbours, maybe there was a bit of that, certainly Petunia was,” she chuckles. “But that would be an act of imagination, but just a limited imagination, and maybe not a generous imagination. Generosity is the thing the kids learn when they get to the school, so they expand into another sphere. And all they do is they expand their minds, really is what they’re doing, magic is expansion, mind expansion.”

“I’m obviously very sorry about Richard... I was in America and I actually was desolate for days after he was gone because we had had the most wonderful time together here.”

“He would regale us with the most marvelous stories, he was a brilliant storyteller and very often the camera could not go to action because Richard was finishing a story,” she laughs. “People were sort of looking at watches and then Richard would say ‘and then what happened…’.”

“He also had the most beautiful handwriting of anybody I’ve ever met. He was trained in calligraphy so his hand-written notes were always beautifully done.”

“Harry Melling is absolutely like a plant that I feel we watered,” she says. “When he was 10 he was one of the most talented young actors of that group. He really was the most ambitious – the others were enjoying it but Harry Melling really wanted to be an actor, and his uncle was an actor, and he took it very seriously.”

“He actually auditioned for the National Youth Theatre while here,” she explains, “and he missed his audition because he was filming so I rang up the National Youth Theatre and said the reason why this young man is not auditioning for you is because he’s filming and they very kindly set another date.”

“I remember this because we practiced it. He did Caliban – all the infections that the sun sucks up – and we rehearsed it here in the gaps and he took off. He later went to drama school and then played my son in Mother Courage at the National Theatre and by then had become this swan of a man. He’s beautiful, talented and I’ve just seen him in the West End being utterly brilliant in Hand to God. He was just astonishing in it. I’m very proud of him.”

“But the scene I keep on referring to is in the kitchen, when the owls wouldn’t look at me. They just wouldn’t look at me, they kept on turning their heads right around like that,” she explains, twisting her neck as far as possible, “like something out of The Exorcist because they kept on looking at the camera.”

“[The crew] hung some mice on my apron so that the owls got absolutely fixated on my apron and looked at me,” she explains, “and I thought, 'there’s something absolutely brilliant about the telling of storytelling, that people go to endless trouble to make something seem like something.' And this set was full of real endeavour by people who were always good humoured, working very hard, a lot of them.”