The BBC has announced that for the first time in 13 years, this year ‘Doctor Who’ will not be showing special episode on Christmas day.

The special has been a fixture of many families’ Christmas schedules since 2005 – and it’s become tradition that when each series’ 10 episodes have aired, an extra 11th is shown on December 25.

This year, an hour-long bonus episode will still air, but instead it will be on New Years’ Day.

The synopsis released by the BBC seems as if the New Year is also relevant to the episode’s plot, stating: “As the New Year begins, a terrifying evil is stirring, from across the centuries of Earth’s history.

“As the Doctor, Ryan, Graham and Yaz return home, will they be able to overcome the threat to planet Earth?”

Chris Chibnall, the show’s writer, confirmed the continuation of the historic 11-episode run in a Comic Con press conference this summer: “We seem to be filming 11 episodes, and it’s only a series of 10,” he said.

Executive producer Matt Strevens added: “I don’t know what happened. It’s a show about space and time, so it’s all quite abstract.”

The BBC hasn’t given a reason for the shift in timing of the bonus episode, but there are a few potential explanations.

Former showrunner Steven Moffat has previously hinted that the writers might be running out of Christmas-themed plot ideas as the years went on.

“I think it was a brilliant idea [in 2005] and it lasted a very, very long time,” he said.

“I sort of think we might have mined and possibly over-mined every single thing we could about Christmas in ‘Doctor Who’”.

It’s also possible that decision-makers at the BBC may simply think a different slot would do better for their ratings – after all, amongst hangovers and families gathering round the TV, New Year’s Day is a competitive slot. Last year ‘Sherlock’ ratings notably were higher than those of the Queen’s Speech.

It hasn’t been announced what time the episode will air, but Radio Times speculates it will be around the 6.30-7.00pm mark.

It has, however, been confirmed that the main gang, comprised of Jodie Whittaker, Mandip Gill, Bradley Walsh and Tosin Cole, will be appearing in the episode.

This series of ‘Doctor Who’ has already become known for changing things up, with Jodie becoming the first woman to play the Doctor in the 55 years since the show began.