“After Harry Potter, all that mattered was university. I didn’t even know if I wanted to be an actress,” she says. Her agent didn’t send her any scripts during her first year. “For a while it was amazing, as the American press afforded me so much privacy.” However, she couldn’t escape her fame. “On the first day, I walked into the canteen and everyone went completely silent and turned around to look at me.” It’s not a memory she relishes. “I had to say to myself, ‘It’s OK, you can do this.’ You just have to take a deep breath and gather your courage. I have moments where I walk into a bar and it will take me making a joke to put people at ease, to realise I am just a girl.”

She dismisses suggestions of problems at Brown, but says: “It wasn’t always easy to break down barriers, as having men from the British press following me with cameras didn’t help my mission to integrate myself.”

She spent a year studying at Oxford “because my parents did, and I wanted to experience it”. However, they couldn’t be less interested in her films. “My dad never watches films and only reads books. And my mum owns, like, four VHS videos. They’re supportive, but they wouldn’t know how to advise me.”

Her parents divorced when she was five, but they still live in Oxford, and Watson is the eldest of her seven half- and step-siblings. “I feel so strongly tethered to England. The people who have known me longest are here.” She pauses, frowning. “The time I remember before I was famous was here too.” The way she refers to these two sections of her life, schoolgirl and global star, reminds me of the way people talk when they have experienced trauma, seeing their lives separated into pre- and post-event. “They are two different parts of my life,” she says carefully. “The time before I was famous is important as it formed who I am, and my closest friends, who I completely trust, are from then. They ground me, which is something I purposely cultivate.”

She’s on Twitter, but is probably slightly disappointing to her 12.4m followers, as there are no selfies or snaps of homemade cakes, even though she enjoys cooking. “Raspberry and amaretto cake is my favourite, but I also like banana choc-chip bread and egg tortilla. Cooking helps me to relax, and I think people close to you appreciate a home-cooked meal,” she adds coyly, although it’s about as close as she’ll get to revealing anything about her newest relationship, with Matt Janney, rugby hunk and Oxford’s most eligible bachelor. “I can’t comment on it, I’m sorry,” she says, suddenly jumping up and hastily bundling her things back into her bag, which has exploded across the sofa beside her. “I’m trying to keep my private life sacred, although I don’t want to lock myself up and never go out. So I guard it, because I don’t date people who are famous, and I don’t think it’s fair that, all of a sudden, intimate details of their personal life are public as a direct result of me. I find that so uncomfortable, and I wish there was a way I could protect those people, but it’s not in my control.”