“Having worked together on and off for the previous decade, while never taking it for granted, we’d slipped into a groove. Once we put the clothes on, you get into a certain rhythm,” says Paddington star Hugh Bonneville, who is back in his role as Robert Crawley, Earl of Grantham.

“But of course the pandemic changed that for everyone and so, when we came together to do the read through, and then on the first day on the set, I think we all really realised how fortunate we were within our industry to be working, when so many thousands were not.

“And also I really appreciated the fact that we were in a show that was much loved, perhaps even more than ever, because we’d had so many messages from around the world, from people saying that they’d revisited the show during lockdown, and it had been a comfort, and watching the show again reminded them of a simpler time, pre-Brexit, pre-Trump, pre-Covid.

“And so I think we all shared a sort of, if not a responsibility, an anticipation that we were doing something that would be giving pleasure to many, many fans around the world and we wanted to up our game and make it as good as possible, so fingers crossed.” 

The new Downton film, once again written by Julian Fellowes, brings the family, as well as the staff keeping things running below stairs, into 1928, at a time of major change.

The Dowager Countess, played by the formidable Dame Maggie Smith, learns she has been left a villa in the South of France in the will of a man she knew many years ago, so half the family decamp to the Riviera to investigate.

Meanwhile, Hollywood comes to Downton when a film crew want to use the big old house to shoot a silent picture.

While the old guard above and below stairs think nothing could be worse than a bunch of awful actors running round the place (ho ho), Lady Mary, played by Michelle Dockery, sees the advantage. The roof is leaking and the film will cover the bills.

Soon the house is besieged by a large crew, including a director, played by Hugh Dancy, and two silent film megastars, played by Dominic West and Laura Haddock. But calamity strikes when the first “talkie” is released, forcing the cast at Downton to find a way to bring their suddenly outdated film into the modern era.

“I hadn’t realised how quickly film moved from the silent films into the talkies,” says Dockery, “and this is loosely based on the true story about this movie called Blackmail, which originally was a silent film and then, when the talkies first came out, everybody was going to them.

“Also I didn’t realise the impact that it might have had on actors at the time, so it’s just so interesting learning about the beginning of film and being part of that as the character.

“I’m always really surprised by what Julian writes and I was quite surprised when I read that Mary becomes involved in the film in ways in which she couldn’t have ever imagined, but it was a nice fit for the character, it was something very new and very fresh.” 

While Mary is getting to grips with the world of modern film-making, her sister, Lady Edith, played by Laura Carmichael, is exploring the new world of holidaymaking in the South of France, as she joins the rest of the family meeting the current owners of the villa bequeathed to the Dowager Countess.

It marks the first time the world of Downton has travelled overseas, and offered a whole new playground for the cast.

“We were thrilled, obviously,” enthuses Carmichael, “because we got to go and spend some time in this beautiful location, but it was also really cool to see that part of the world at this time.

“Edith becomes interested in travelling with them so she can write an article about the fact the rich and famous were starting to have holidays and vacations in the South of France and it had become very fashionable, so you really get to see how how the fashion was happening there and how the jazz era was all there in France, so it was great fun.” 

“It was a way to have every character open up because they’re in this different environment, and it’s a more relaxed environment and things happen that wouldn’t necessarily happen back at Highclere Castle (the location where Downton Abbey is filmed), so it was a wonderful device,” adds Elizabeth McGovern, who returns as Cora Crawley.

“And Cora shares a secret that she’s been harbouring for a really long time, and Robert is losing his stiff upper lip.

“It’s the kind of thing that often happens to me when I read Julian’s writing – there’s more on the page than first meets the eye, and it takes the whole crew and all the actors coming together for you to realise all the depth that’s actually in this writing, that I don’t even know if he’s aware of when he writes.”

• Downton Abbey: A New Era is in cinemas on Friday, April 29