Hugh Bonneville on the reasons Downton Abbey has been so phenomenally popular

Inevitably Downton looms large in Playing Under the Piano: From Downton to Darkest Peru, the new memoir from Hugh Bonneville who has played Robert Crawley, Earl of Grantham, throughout the TV series and across two films.

Hugh, who will be talking about the book on October 30 at 7.30pm at Rother College Theatre, Midhurst for the Petworth Festival Literary Week, says it's impossible to put a finger on just why it has gripped the world in the way it has: “I think whenever you are creating something, no one sets out to make a bad movie or whatever, but the fact is sometimes the elements just align and something just gels along the way. But I do think it has to come down to the writing. Julian (Fellowes) writes from the default that people are trying to be good. I think there is an underlying benevolence to the series that those that wave the people’s flag find very annoying and disgusting when they think that all people with inherited wealth must be evil. But the fact is that the series is about people who are trying to be good.”

There have now been two Downton films: “And I think the second was better than the first. It became more cinematic. I was nervous beforehand that the film would just be another television episode with bigger cameras but the really key thing I think was with the audience – the people who would usually be watching alone at home or perhaps with their families or in viewing parties or whatever. But suddenly in the cinema there were hundreds of people all watching at the same time. And it's that great collective experience that you have in the cinema that makes the difference. It was that great collective experience at the cinema that helped take things to another level. I have crept into screenings in the past where people were actually applauding the film and you just never see that in the cinema these days.”

Another key part of Hugh’s book inevitably focuses on Paddington, again of which there have been two films made. But with Paddington, a third has now been announced, Paddington in Peru: “I don't know what is going to happen. There was talk of it starting this year and then there were issues quite literally with the leaves on the trees in Peru or something. I just don't know. I have not seen the finished script and I don't know more than that.”

But it's been a remarkable duo of successes across two very different strands for Hugh – though as he points out maybe they are closer than you would think: “I play a bit fuddled father in both of them!”

In the meantime of course we have seen Hugh in very different guise in the Netflix thriller I Came By: “And that was very refreshing. It was very nice to do.

"When casting directors see you, they might think ‘Oh you are not right for this job’ and you have to go and to dredge up something like Daniel Deronda to see me playing someone that had a certain menace. But this was great. Every actor wants to flex their muscles and I do think every actor likes to show what they can do. People seem to have enjoyed me playing someone very different to what they usually know me for.”