Game Of Thrones star Kit Harington will portray one of his ancestors when new BBC drama Gunpowder debuts tonight.

The actor, best known for his role of Jon Snow in the smash hit Sky Atlantic fantasy epic, stars opposite Liv Tyler in the drama as Robert Catesby, a Warwickshire man who was the mastermind behind the plan to blow up the Houses of Parliament on November 5 in 1605.

Kit Harington in Gunpowder (Robert Viglaski/BBC)

He said: “My mother’s maiden name is Catesby. My middle name is Catesby, so way back when we were thinking about doing this piece, I kind of knew I wanted to be in it and I knew it would hopefully help get it made, but I didn’t know if I wanted to be Fawkes or Catesby or which of the plotters.

“So I wasn’t aiming to play my ancestor – it just so happened that Catesby was the one that fitted.

“You go that far back and everyone is related to everyone, really.”

Kit Harington (Robert Viglaski/BBC)

He added: “It’s one of those pieces of family things that you go, ‘oh do you know that you’re related to so and so’ and you’ve grown up with that in the background of your knowledge, going ‘oh well that’s quite interesting – it’s something to tell at dinner parties’, but I didn’t know the story so well.

“I knew that Robert Catesby was the leader of the gunpowder plot and so as a kid I would kind of go, ‘it wasn’t Guy Fawkes, it was Robert Catesby’, but I didn’t know any more than that, so it kind of came about in me knowing that strange quirk in my family history.

“But I learned about this through thinking about this piece, rather than knowing all about this piece of history and therefore wanting to make a piece about it.

Gunpowder begins on October 21 at 9.10pm on BBC One.