It may seem strange that one of the most anticipated films of 2017 should be a live-action remake of a Disney cartoon about Stockholm syndrome, but Beauty and the Beast has already built up the kind of fan base that is normally reserved for rebooted sci-fi franchises and adaptations of erotic bestsellers. When the first trailer went online in November, it was viewed a record 127m times in 24 hours, beating the previous leaders in that particular field, Star Wars: The Force Awakens and Fifty Shades Darker. Stranger still, 27m of those views were on the Facebook page of the film’s star, Emma Watson.

That figure might suggest that the 26-year-old who played Hermione Granger in the Harry Potter series is now a bona fide superstar. But Watson’s celebrity status is slightly more complicated. As a Hollywood player, she isn’t going to give Jennifer Lawrence or Scarlett Johansson sleepless nights, but as an actor-activist she has the kind of influence that would have been unimaginable a generation ago.

For proof that Watson isn’t yet an A-lister, you just have to glance at her filmography since she hung up her Gryffindor robes. Broadly speaking, she has taken supporting roles in ensemble projects, such as Simon Curtis’s My Week with Marilyn and Darren Aronofsky’s Noah, and above-the-title roles in films that vanished without trace. Alejandro Amenábar’s repressed-memory chiller Regression didn’t recoup its $20m budget, and Colonia (AKA The Colony) pulled in a grand total of £47 in its opening weekend in the UK. Meanwhile, she turned down the title role in Kenneth Branagh’s Cinderella, and accepted then dropped out of La La Land, thus handing Emma Stone the part that may well win her a best actress Oscar. In the years between Harry Potter and Beauty and the Beast, in other words, Watson was better known for films she wasn’t in than for films she was.

‘She is clearly not an activist of the old school’ ... Emma Watson at the Noah film premiere in New York. Photograph: Startraks Photo/Rex Shutterstock

In contrast, Kristen Stewart followed her stint in the Twilight series by embracing arthouse cinema and being embraced right back: she was the first American female actor to win a César award for her performance in Clouds of Sils Maria. And Harry Potter himself, Daniel Radcliffe, has grabbed every possible acting opportunity, from big-budget capers (Now You See Me 2) to indie curios (Swiss Army Man), from television (A Young Doctor’s Casebook) to theatre (Rosencrantz & Guildenstern are Dead). Compared to them, Watson is barely trying.

But there is more on her mind than acting. Having stepped away from the business to study for an English degree at Brown University in Rhode Island, she now spends as much time on feminism as she does on films. In 2014, she became a UN Women goodwill ambassador; in 2015, she was named on the Time 100 list of world’s most influential people, and last year she continued to make headlines by, for example, leaving feminist books around the London Underground system.

None of that may appear very remarkable: Watson isn’t the first film star to double as a political activist. But few stars can have been as reassuring or inclusive in their consciousness-raising. When Angelina Jolie and Leonardo DiCaprio signed up to humanitarian and environmental causes, for instance, they were already untouchably glamorous demigods whose lives seemed a million miles away from their fans’, and whose jet-setting activism seemed almost as distant. Watson is different. She may have flown to Bangladesh, Uruguay and Zambia on behalf of the UN, but she doesn’t come across as if she is lecturing her fans from on high – more as if she is learning alongside them.

The first reason for this is that Watson’s fans feel, with some justification, that they know her. Not only have they watched her growing up onscreen in eight blockbusters, but they have heard her admit that the character she played in those blockbusters was just like her. In an interview with feminist author bell hooks in Paper magazine, she said that when she started reading JK Rowling’s novels, at the age of eight, “the character of Hermione gave me permission to be who I was,” ie, “the girl in school whose hand shot up to answer the questions”. But when she was cast as Hermione she used her earliest interviews to deny she was that girl: “At first I was really trying to say, ‘I’m not like Hermione. I’m into fashion and I’m much cooler than she is,’ and then I came to a place of acceptance. Actually, we do have a lot in common. There are obviously differences, but there are a lot of ways that I’m very similar. And I stopped fighting that!”

Watson during the Women’s March on Washington. Photograph: Jose Luis Magana/AP

If Watson-watchers believe she is just as earnest, studious and intelligent as Hermione, then, they have her permission. Whereas so many former child stars have shattered their youthful images, either by going off the rails in their personal lives (eg, Drew Barrymore) or choosing to play edgy, sexualised roles on film (eg, Dakota Fanning), Watson has been brave enough to carry on being the school swot. The youngsters who identified with her when they saw her in Harry Potter and the Philosopher’s Stone in 2001 can feel that she has yet to let them down, nearly 16 years later.

Even her activism is bound up with that swottiness. Rather than manning the barricades, Watson has focused on reading, discussion, and chronicling her studies on social media, thus making them accessible in a way that would once have been impossible. Last year, she set up a Goodreads online book club, Our Shared Shelf, which recommends a text to its 168,000 members every two months. Its current book is Eve Ensler’s The Vagina Monologues. “There is so much amazing stuff out there,” Watson enthuses on the club’s homepage. “Funny, inspiring, sad, thought-provoking, empowering! I’ve been discovering so much that, at times, I’ve felt like my head was about to explode.”

Again, these are hardly the pronouncements of a Tinseltown divinity, but the sincere effusions of someone who is really getting into her homework project, and who wants her friends to get into it, too. It is no wonder Watson’s fans have taken to feminism with her. And it’s no wonder those fans are so thrilled about her starring role as Belle in Beauty and the Beast.

Watson distributing free copies of Maya Angelou’s Mom & Me & Mom on the London tube.

Watson rejected the part of Cinderella, she has said, because the passive character didn’t “resonate” with her. But Belle is a more Hermione-ish heroine. In the original 1991 cartoon, she wasn’t content to do the housework with the help of some chirruping bluebirds: she strolled through town with her nose in a book. And Watson told Total Film magazine that she had pushed the character even further from the traditional Disney doormat, so as to ensure that she is “the kind of woman I would want to embody as a role model”. She isn’t just Belle, but bell hooks. Never before has there been such continuity between an actress’s online persona and her two most iconic roles.

Of course, Watson is still playing a fairytale heroine in a film with “Beauty” in the title, so she isn’t exactly dismantling the patriarchy. “She’s a very useful figure for feminism, because she attracts people who might not be drawn to it in another form,” says Professor Diane Negra, the author of What a Girl Wants: Fantasising the Reclamation of Self in Postfeminism. “But she is a particularly palatable version of a feminist celebrity. She is a very glamorous and polished figure with all the markers of privilege. She is clearly not an activist of the old school.”

One way to understand Watson’s very 21st-century celebrity activism is to see her as a multi-hyphenate entrepreneur in the vein of Beyoncé and Gwyneth Paltrow. It’s just that instead of using her brand to promote her own range of perfumes and cookbooks, she is using it to promote gender equality. And if Disney gets a ton of free advertising along the way, so be it. For every hundred Watson fans who go to see her in Beauty and the Beast, there will be one who reads The Vagina Monologues on the bus home.

• Beauty and the Beast is released on 17 March