Emerald Fennell wanted to write stories "about murder" from the age of seven.

Emerald Fennell

Emerald Fennell

The 35-year-old writer-and-actress has loved stories since she was a child and frequently read late into the night because she suffered from insomnia, which fuelled her "dark" imagination.

She said: "I had really bad insomnia, and reading has always been kind of a lifeboat.

"Writing replaced reading at some point. And my imagination was quite dark.”

As a young reader, she said she "liked things that were set in high school where cheerleaders were being murdered", and she revealed her mother still has a video of her from when she was seven.

In the clip, Emerald announced: "I want to be an actress or a writer. I want to write stories about murder.”

The 'Crown' star has written the book for Andrew Lloyd Webber's 'Cinderella' and revealed her take on the story is more like "Disneyland on crack" than the classic fairytale.

She told WSJ. magazine: "[Cinderella is] disruptive...and she’s funny and sharp.

"[Andrew] said he wanted something new and different. It’s Disneyland on crack.

“Cinderella in the traditional story barely has a character; terrible things happen to her. Then she is saved by a fairy godmother and a prince. It’s not a story most people nowadays are going to be that invested in. You want to see someone...be the engine of their own destiny.”

Meanwhile, Emerald admitted she has loved playing Camilla Parker-Bowles - who is now known as the Duchess of Cornwall since her marriage to Prince Charles - in 'The Crown' because she's "not a fairytale character".

She said: "That’s the great thing about Camilla. She’s just not a fairytale character. She’s this person who wasn’t wanting to be part of it at all, but regrettably fell in love with somebody right at the centre of it.”