Hugh Bonneville has promised Downton Abbey fans that this year’s Christmas special will have a “festive” feel.

For the last couple of years, the period drama’s seasonal specials haven’t been too Christmassy, but Hugh revealed that the instalment on December 25 will be set during the Christmas period.

“I think audiences will really enjoy this one. It has a lovely festive element to it,” he said.

The actor – who plays the show’s patriarch Lord Grantham – was tight-lipped about the plot but revealed that “a chunk of” scenes have been shot at Alnwick Castle.

A handout picture of the cast of Downton Abbey
Hugh Bonneville wouldn’t divulge any plot details about the Downton Christmas special (ITV)

“Highclere [Castle, where Downton is usually shot] is stunning to film in but frankly, Alnwick Castle is huge. That was the highlight of the year,” said Hugh, 51.

“Harry Potter filmed exteriors there, but I believe it’s the first time cameras have been allowed inside. The Duke and Duchess of Northumberland are huge fans, which is why they let us in.”

Downton has become a phenomenon since it first aired in 2010, but Hugh said he didn’t fully realise how big it was until an encounter in a playground.

“A kid in my son’s school came up to me,” he recalled. “He was about nine and said, ‘I don’t like what that Thomas [Downton's conniving footman] is doing’. I’d never, in a million years, thought it would appeal to those that young, but kids and grandparents are watching it together.”

Downton Abbey will air on ITV tonight.