Simon Callow on starring in The Amazing Mr Blunden remake: "I had never even heard of the film before"

As in the previous 1972 film (and Antonia Barber's 1969 novel The Ghosts on which it was based), the story centres on teenagers Jamie and Lucy Allen, who are approached by the titular Blunden with rather an unusual job offer for their mother: the opportunity to become the caretaker of a run-down country house. Although initially reluctant to make the journey, Jamie and Lucy quickly discover that their new home is full of fascinating secrets, and an encounter with a pair of ghostly children soon leads them to a vital mission – all of which links back to Mr Blunden. Callow had previously worked with Lionel Jeffries, who directed the previous adaptation, but he confesses that he "had never even heard of the film" before Gatiss got in touch about the role last December – when he was working on a job in Atlanta, Georgia.

"Mark sent me a text saying there's a very early Christmas present coming for you," he explains. "And a week later I got the script, and I was just entranced by it, so much so that I immediately wanted to see the film, but there was no way that I could get hold of the film. And by amazing chance in Atlanta there's a bookshop that had a copy of The Ghosts. So my first encounter with the material – apart from Mark's script, of course – was Antonia Barber's novel, which is really very good, very, very readable and very resonant."

Both Jeffries' film and the new version make a couple of changes from Barber's text, most crucially presenting the story as a Christmas tale rather than an Easter one. And although Callow says that it's very clear from the novel that it's a very Christian story about redemption, he thinks the change of setting makes a lot of sense. "Both Lionel and Mark made exactly the right decision to set it at Christmas," he says. "Because, especially for us now in a mostly secular world, it's just sort of a celebration of generosity and benevolence and innocence in a way. That's what both Mark and Lionel focused on, and I think it's exactly the right way to have gone and made it very rewarding.

"Blunden, certainly the Mr Blunden who visits the children and their mother for the first time, is a man suffused with benevolence and generosity, a man who wants to put right the awful things he did 200 years before, roaming the globe looking for a way to revisit his past and eliminate the terrible thing that he did, and so I think that links up to Christmas in some kind of way, just the kindness and goodness and the sweetness at the heart of Mr Blunden."

Reworking classics can often be a tricky task, with radical changes to iconic texts just as likely to inspire accusations of blasphemy as they are to garner praise for originality. So given Callow's longstanding relationship with A Christmas Carol – a story that has been successfully reworked more than just about any other – I wondered what he thinks is the key to getting an adaptation right.

"I think you really need to go back to what was the original author thinking about," he explains. "In this case, what was she trying to say and how do we tell that as well as we can to an audience today while at the same time keeping the originality of what she wrote. And that is a bit of a balancing act. One very clear example of this is that Mark has decided to set it now, in a very recongisable London – that immediately gives it actuality, makes it now, so we aren't thinking 'Oh this is something that would only have happened 20 or 40 or 50 years ago.'

"I think you have quite a bit of freedom," he adds. "But the odd thing is that plays are intended basically to be done over and over again in different ways whereas mostly screenplays are only shot once. It has increasingly happened over the history of film that people have made a story so good that it needs constantly to be remade, like A Star Is Born – here must be something like four versions of A Star Is Born, and they all have something to say. But generally speaking, when you revise a play you're going to do it as it was written, whereas screenplays will probably be rewritten – but the basic story becomes part of the collective unconscious, it belongs to all of us, a story like A Star Is Born. And so the great thing is to do it with real sensitivity to the original story, sensitivity to what it's about rather than slavish imitation."

Another minor alteration to the previous version is the manner in which Callow plays Blunden himself. He admits to being a huge fan of Laurence Naismith, who played the role in the original, but said he wanted to take the character in a slightly different direction with his portrayal. "I did see it [the original] eventually but I just sort of almost turned away from the screen when Naismith was on," he says. "Because I always knew that I wanted my Blunden to be a little more emotionally available than Naismith. Naismith plays it with a pretty stiff upper lip, but I wanted Blunden to be very, very vulnerable and very poetic, and because we put in a bit more about the wheel of time idea, which underpins the whole film. I think he's a bit of a visionary as well – he's been in touch with the mystery. I wanted to show that if I could."

The Amazing Mr Blunden hasn't been Callow's only big project of late – he's also popped up in small roles in two of the biggest television events of this Winter, namely Hawkeye and The Witcher. Callow speaks enthusiastically about his work on both projects, although he does rather lightheartedly rue his swift demise in the former.

"It's huge," he says of working on an MCU project. "There was a huge number of people, a huge number of camera crew, and tremendous energy and need to get it all done very quickly, so it was very much like being in a big American movie, being in Hawkeye. And as it happened, my character was summarily dispatched pretty quickly – I was barely there before I was dead! Which is of a piece with a lot of my film career. It seems there's a great demand on the part of the public to see me dead – every other film that I make I have to die!"

He laughs and then adds: "I'm perfectly prepared to do that if it pleases people. Give the people what they want, I say! I also did something in The Witcher – and that, amazingly enough, I didn't die in, so I think you'll see more of me in The Witcher, which was delightful to do."

Alongside Callow's extensive screen work, for much of his career he has been totally immersed in the theatre, as both an actor and director. And although he was encouraged by the audiences that returned to theatres following the post-lockdown re-opening last summer, he admits these are still immensely worrying times for the industry.

"We mustn't forget the people who have pretty well gone down," he says. "Companies that have gone down, theatres that have closed, actors that have decided that they can't endure it anymore, the uncertainty of it all. It's uncertain enough as it was but now there's huge uncertainty all the way round. Big productions with masses of advanced bookings can just about take the hit, but a company that hasn't got that will struggle – there is still no government insurance for theatre shows.

"It's been a very, very alarming time, no question about it," he continues. "And it has been really encouraging in the past few months to sit in theatres, or concert halls and be surrounded. This is an activity that we've been engaging in I suspect from the dawn of time, whether it was in a cave or somewhere outside the main settlements of Neanderthal people, I'm sure something like theatre was going on. It's a very fundamental experience for us, telling stories and listening to stories in the company of our fellow citizens – it's a life-enhancing experience.

"And now, the trouble is it's very cost-intensive. We've passed beyond the point where you can put up a trestle table in the middle of the marketplace and jump up and do your thing, we expect more from the theatre with the wonderful technology and so on we've got, but it's all expensive and the producers who put on plays or repertory theatres who put on plays have to fight so hard to make ends meet. Most shows in the West End, even ones that have been on for some while, just about break even. So we desperately need a climate in which people feel free and excited to go to the theatre."

The Amazing Mr Blunden will air on Sky Max and streaming service NOW this Christmas. Looking for something else to watch? Check out our TV Guide or visit our dedicated Fantasy hub for the latest news.

This year’s Radio Times Christmas double issue is on sale now, featuring two weeks of TV, film and radio listings, reviews, features and interviews with the stars.