Mordred will be returning in Merlin’s fifth series, although the character will be played by a different, older actor.

24-year-old Alexander Vlahos now takes the role of the Druid destined to be responsible for Arthur’s death.

Vlahos wrote on his twitter account: “I’m surprised how the news got out. I haven’t told a soul.”

Mordred appeared in three episodes previously, portrayed by the much younger Asa Butterfield.

The age increase suggests a large time jump when we resume the series, which fits in with earlier hints dropped by Merlin co-creators Johnny Capps and Julian Murphy.

“All the characters will have moved on a lot. When we start, I think everyone will be surprised where all the characters are,” said Capps in magazine SciFi Now.

Murphy also teased: “I would never rule out the return Mordred. That’s a possibility. He has a job to do at the end of the story.”