The creators of Stranger Things have said their upcoming stage show, based on their hit supernatural Netflix series, is a possibility they “never expected”.

Matt and Ross Duffer said the concept had not been “not part of the original plans” when they first wrote it for television eight years ago.

The duo told the BBC there were more spin-off ideas in the works, but said taking the series to the stage is “completely new ground”.

Presented by Netflix and Sonia Friedman Productions, the new play, called Stranger Things: The First Shadow, will premiere in London’s West End in 14 December 2023.

The spin-off prequel will take place in the same universe as the much-loved TV series.

Ross Duffer spoke of his surprise at the TV show’s success.

“When we made that first season, we were just shocked we were allowed to make a show, so to see what it has become, and now the world is starting to expand, is pretty great. But this is something we never expected,” he said.

Stranger Things debuted on Netflix in 2016. Nine years and 12 Emmy Awards later, the show is still garnering record-breaking viewing figures.

The fourth season was released in 2022 and currently tops the Netflix most popular English TV list, with over 1.35 billion viewing hour. It also became the biggest premiere weekend ever for an English-language TV show on the streaming service.

The new play is written by Stranger Things writer Kate Trefry and directed by three-time Tony Award-winning director Stephen Daldry.

Daldry was also Oscar-nominated for The Reader, The Hours and Billy Elliot and is executive producer on the TV series The Crown.

Asked how the idea for a theatre production came about, Matt Duffer explained: “The idea did not come from us. I don’t think I would have had the idea. The idea came from Stephen Daldry.”

“Daldry was a big fan of the show and wanted to do a play, but he was so busy with The Crown that I thought this would never happen. Finally a window opened up, he came back and expressed his interest again, and we met up with him and started to talk about what the play could be.”

He added that Daldry had firm ideas about what he had in mind.

“I think when I first heard play, you immediately think it’s going to be a musical of season one or something like that. He was not interested in that kind of thing at all. He wanted to tell a new and original story,” he said.