Downton Abbey's festive farewell, starring Alnwick, watched by 9.6m in the US

Hugh Bonneville, who plays the Earl of Grantham in Downton Abbey, pictured in the library at Alnwick Castle.

It has resulted in a boost of interest in Northumberland from Americans, as it attracted 9.6million viewers, the highest-rated episode of Downton that wasn’t a series premiere..

Broadcaster PBS, which part-funds the hit period drama, showed the series swansong on Sunday at 9pm (2am UK time).

A scene from Downton Abbey's Christmas Day episode set at Alnwick Castle.

Kenton Keithly, of Woodland, California, who has been a regular visitor to Alnwick for the past 15 years, watched the episode.

He said: “It was wonderful to see the shots of the castle from the Lion Bridge, which really brought home how huge it is,” said Kenton, 64, who runs a janitorial business. “We’re used to seeing the grandeur of Downton Abbey in the show, but it reached a whole new level when we saw the opulence inside Alnwick Castle.

“It was a perfect backdrop for the final episode of a show which is huge here in the US. Knowing many of the folk of Alnwick, I was also struck by how little has changed over the years in terms of the British class system, too. There’s still very much that hierarchy in place, something Americans have little experience of and may be surprised actually still exists.”

Tourism bosses at Northumberland Tourism have noticed an uplift in interest in the county, and especially Alnwick, from the States

Kenton Keithly, who watched the last episode of Downton Abbey, which was partly filmed in Alnwick, from his home in Woodland, California.

Jude Leitch, director of Northumberland Tourism, said there had been a spike in US visitors to the organisation’s website in the hours after Downton had aired in America. There had been 570 visits from the US, up 300% on the previous Monday.

“We are so grateful to programmes like Downton, Vera and Tales From Northumberland,” said Jude. “We could not afford the sort of publicity these bring, especially abroad.”

The festive farewell was watched by 10.92million people in the UK, making it one of the top 40 most-watched programmes of 2015.

Before the catch-up figures were added, the audience stood at 6.9million.