Pallade Veneta - Roald Dahl's 'Matilda' opens London Film Festival

The latest dramatisation of Dahl's 1988 novel about an extraordinary little girl with a vivid imagination and a sharp mind is based on the award-winning musical that launched in London in 2011.

The trio behind the stage hit -- director Matthew Warchus, writer Dennis Kelly and composer Tim Minchin -- have reunited to bring the eagerly awaited re-telling to the big and small screen through Netflix.

The streaming giant has acquired the whole works of Dahl from the late British author's family, with new adaptations of "Charlie and the Chocolate Factory" and "James and the Giant Peach" also imminent.

For Thompson, who plays terrifying headmistress Agatha Trunchbull, the legendary children's writer was "extraordinary" in finding a balance between the whimsy and the bleaker realities of life.

"There's real darkness and you don't want to want to sugar-coat it, but it can't be too real," she told a news conference before the premiere of "Matilda: the Musical" in the British capital.

"It's got to be frightening but you've got to be able to contain it and get kind of a thrill from it... because children see everything."

- 'Gritty' -

The two-time Academy Award winner said making work for children was "sacred" because "they need to get the best of us as artists".

"Then they'll take that as they grow older, and everything useful gets knocked out of them by school," she seemingly half-joked, before asking: "Can I say that out loud?"

Thompson, who wore prosthetics and various creative costumes to play a highly imposing version of Trunchbull, called it the most physically demanding role of her award-laden career.

It took six people and several hours to prepare for each day's filming, she said.

Like the book, the film is a celebration of childhood, creative freedom and rebellion, though this time through stunningly choreographed ensemble song performances made famous by the stage hit.

Australian comedian-composer Minchin penned one new song to bring the curtain down on the new movie, which follows a 1996 version with Danny DeVito.

Although on the face of it a family-friendly musical, this re-telling is heavy with socio-political messaging as it releases into a world gripped by cost-of-living fears, widening inequality and war in mainland Europe.

British actor Stephen Graham, who plays Matilda's heartless and uncaring father, said he was initially unsure whether he suited the part, recalling telling Warchus he stuck to "gritty social realism" roles.

"(He) said: 'It is gritty social realism!'"

- Diverse cast -

The cast is distinctly diverse, with new James Bond franchise actress Lashana Lynch playing Miss Honey, Matilda's beloved teacher and eventual guardian.

The 34-year-old black British actress told reporters playing the part felt like a spiritual gift after she had her own inspiring teacher growing up.

"I'm grateful that we actually had a shift in the film and have a black woman playing Miss Honey," she added.

"Because whilst it doesn't matter -- it's just a person playing her -- it is a clear message for me and my childhood that the black woman that bestowed a lot of wisdom in me at school did the right thing."

Despite the A-list cast, they are in danger of being upstaged by 13-year-old Alisha Weir, who dazzles as Matilda.

"I was really nervous because it was my first big film... working with those amazing people is quite scary," she admitted, adding her co-stars flanking her were fantastic people and "so nice" on-set.

In playing the leading role, Weir said she simply tried to put herself in her character's shoes and channel "how clever she is, and how courageous and brave".

After its unveiling in London, "Matilda" will be shown in cinemas from later this year before hitting the small screen through Netflix.

Now in its 66th year, the 12-day London Film Festival also features the premiere of the streaming platform's animated version of the classic "Pinocchio", directed by Oscar winner Guillermo del Toro.

Another Netflix blockbuster "Glass Onion: A Knives Out Mystery" -- a sequel to the 2019 edition and again starring Daniel Craig -- will close it on October 16.

R.Zarlengo--PV