Emma Watson says she felt “quite overwhelmed” before reuniting with members of the original cast of the Harry Potter movies for a one-off TV special.

But the actress, who played bookworm Hermione Granger, ended up being “pleasantly surprised” to relive the years spent making the eight-film series.

The movies, which took 10 years to film while Watson and her co-stars Daniel Radcliffe and Rupert Grint were mostly teenagers, propelled the youngsters to international fame.

In a clip released by HBO Max, which produced the special, she said: ” Some of us haven’t seen each other for years.

“It’s just been a joy, an unexpected joy. I really didn’t know how it would feel.

She added: “I felt quite overwhelmed this morning and I’ve just been quite pleasantly surprised by just getting to relive it all.

In an earlier clip, she said: “It feels like no time has passed and loads of time has passed.”

When is the programme on?

In Return to Hogwarts, which airs on Sky and streaming service Now TV from New Years Day, Watson is filmed being reunited with Radcliffe, Grint and a host of other famous faces on the 20th anniversary of the release of Harry Potter and the Philosopher’s Stone, the first film in the series.

They joined the director of the first two films, Chris Columbus, to discuss the beloved movies and explore their creation.

Since the films were released, the author of the books on which they are based, JK Rowling, has attracted controversy over her comments on transgender identity, including from stars Watson, Radcliffe and Grint.

Rowling’s new books now a spin-off series

Rowling, 56, whose books have continued to be turned into films in a spin-off prequel series, has said she was partly motivated to speak out about transgender issues because of her experience of domestic abuse and sexual assault.

Actor Chris Rankin, who played Percy Weasley in the series, is the latest actor to address her comments, telling the Eastern Daily Press newspaper: “I do a lot of work with charities that are LGBTQ+-focused… A lot of my family are members of the community.

“It is a huge part of my life and I think, by saying that, you can probably guess where my allegiances lie in that respect.

“What is important to highlight is that, when a trans person says they are male or female, that is what they are and that is how we should treat them. It is damaging to them to say otherwise.”