Paul Giamatti says that Dame Maggie Smith "still feels present" in 'Downton Abbey: The Grand Finale'

Paul told People: "It was not the same without her, but it felt very much like in her honour in some way. She certainly still feels present through the whole thing.

"Not having her there is obviously a huge loss, but everybody was still acting in her spirit."

'The Holdovers' actor added: "Working with her the first time around was one of the best things ever and I didn't even really get to do that much with her."

Paul was surprised to return for the movie after appearing in the 'Downton Abbey' TV series back in 2013 but teased that his alter ego has a "significant" role in the film, which is slated for release in September.

He explained: "The interesting thing for me was that they even asked me at all because I was like, 'I don't have an important character in this story.'

"But what's funny is my character has a very significant role. He does something very significant in the movie. I was like, 'It's really funny they brought me back to do this this very important, significant thing.'"

Although he was shocked to be asked back, Giamatti admits that he thoroughly enjoyed his return to 'Downton Abbey'.

He said: "When you walk into a thing where the culture is so set, they know what they're doing, everybody's happy doing it, everybody's on board with doing it, it's really nice.

"Those people were awesome and I was looking forward to going back there because I had such a fun time the first time around. It was lovely."

Paul features in the new season of Netflix anthology series 'Black Mirror' as an isolated man who is introduced to a system that allows him to step back into old photographs - although he regrets to admit that he is no slave to nostalgia.

He said: "I'm not a big nostalgia guy and I don't have a ton of photos. I regret that now. I wish I had kept a lot of things - photographs, but also letters, school papers, tests, reports. I never kept anything. I was always just thinking: 'What's next?'"