However, she said she hoped her version would entrance newcomers as much as Dickens’s most stalwart fans.

The latter, she admitted, can be hard to please.

“It’s difficult enough putting novels on the telly when you have to leave a lot out and you annoy a lot of the fans,” she said.

“Now, here was I proposing not only to leave a lot out, but to put a lot in.”

Charles Dickens died before finishing the book, which deals with the story of drug-addicted choirmaster John Jasper.

The Mystery of Edwin Drood is a “dark and gothic” tale which is “very spooky, scary and modern,” said Ms Hughes.

Faced with the task of finishing a story which Dickens began just over a century and a half before, Ms Hughes said she faced working with a plethora of “fantastically vivid characters”.

“I enjoyed their company even as I wrestled with the hideous hell of making a plot that worked.

“What I’ve done is to concentrate on the characters at the centre of the drama. It’s Dickens, so there are tons of people in it who are all being funny and grotesque.

“In a thriller like this they don’t really work so, with huge apologies to fans of the book, I really concentrate on the central character.”

She said that, though she might think twice before taking on such a task again, the whole process of finally solving a classic Victorian mystery had been “great fun”.

She said finishing The Mystery Of Edwin Drood had only confirmed her admiration for Dickens.

Ms Hughes trained as a newspaper journalist in the north of England, before becoming a BAFTA-nominated television documentary director, specialising in crime and history.

As a writer of TV drama, she started on ITV’s police drama The Bill and BBC One’s forensic crime drama Silent Witness.

She then wrote two award-winning dramatised true stories: Cherished, for the BBC, which was based on the true story of Angela Cannings, who was wrongly convicted of killing two of her children, and Mysterious Creatures, for ITV, which dealt with the story of a couple who struggle to cope with their daughter’s Asperger’s Syndrome.

Her other credits include the ITV drama Blood Strangers, starring Caroline Quentin and Paul McGann, which was nominated for a Prix Italia.

The Mystery of Edwin Drood is available to watch on BBC iPlayer.