Amid all the explosions, battles and high-stakes moments in new Star Wars prequel/spin-off Rogue One, perhaps the most breathtaking was the appearance of one familiar character, who audiences had never expected to see walk into shot.

Now, if you don’t want to know who that character or actor is (a few reviews have revealed it already), look away from this article. They turn up quite early on so it’s not a massive spoiler, but if you like to keep your cinemagoing experience fresh a quick exit might be in order. Spoilers coming after the break.

Read on at your own risk…

Reasonably early in the film, Ben Mendelsohn’s new villain Director Orson Krennic is brought to meet his superior officer – Governer Wilhuff "Grand Moff" Tarkin, played in the original 1977 by veteran Hammer horror actor Peter Cushing. 

Obviously, it makes total sense for Tarkin to be there – the film is set only shortly before the original Star Wars, and he was in charge then – but Cushing passed away in 1994, so you might have expected director Gareth Edwards to recast the role, as he did for Original Trilogy actor Mon Mothma (originally Caroline Blakiston, now Genevieve O’Reilly, who previously played the character in a deleted scene for Revenge of the Sith 11 years ago).

But that’s not what Edwards did. Instead, audiences may be surprised to see Cushing once again performing the role, brought back to the screen more than 20 years after his death through a combination of live-action acting, cutting-edge special effects – and an actor from Holby City.

“It was a lot of blood, sweat and tears from [special effects and animation studio] Industrial Light and Magic,” Edwards told RadioTimes.com of Cushing’s return. “John Knoll, whose idea it was to make this film, pitched the idea of doing the opening text of A New Hope as a movie, to Lucasfilm.

Peter Cushing as Grand Moff Tarkin in the original Star Wars film

“And so he’s always been very aggressive pushing the envelope with what visual effects can do. We were talking about it, and you sort of lay out the movie, and as you start laying it you go ‘you know what, you’ve gotta have these certain characters in there, and I dunno how we’d do it'. 

“'Like, what do we do? Do we cast someone who looks like them? Do we not have them? Do we just hear about them?'”

But as Edwards went on to explain, visual effects supervisor Knoll had a different approach in mind.

“John was always like ‘no we can do this, we can do it, we can do it,’” the director recalled. “He was very confident, and we… you know, to be honest, a lot of people were nervous the whole time, like ‘is this gonna happen?’ And then we went all or nothing in.”

So with the effects idea committed to, the team just needed an actor to portray Tarkin’s physical presence before being altered in post-production – and in a surprising development, they looked no further than classic BBC hospital soap opera Holby City.

Guy Henry as Henrik Hanssen in Holby City

“It was played by an actor called Guy Henry [above], who’s in Holby City, and he was amazing,” Edwards revealed.

UK viewers will know Henry as Director of Surgery Henrik Hanssen in Holby, in which he has appeared on and off since 2010, as well as for roles in Harry Potter and the Deathly Hallows (where he played Minister of Magic Pius Thicknesse), Rome and Starter for Ten, with the actor most recently appearing in daytime period drama The Moonstone.

Rumours of Henry’s involvement have been circulating round Rogue One for some time, as well as the possibility that he could play a younger Grand Moff Tarkin – though no-one predicted that he would be bringing Cushing’s version of the character back so directly.

“It was a massive thing for him, it was very gracious of him, because essentially he’s doing this big performance and getting zero credit for it,” Edwards went on.

“He was gonna be totally replaced, and then had to keep it all secret. So, um, that was a big ask.”

Still, in the end we have to say Henry pulled it off rather well – and without giving too much away, we can say that his Tarkin is not the only original series character to come back with a little movie magic.

“I mean ideally, you get the original actors to play these roles, but it’s been 30-odd years since then, and so it’s impossible,” Edwards explained.

“People have aged so much that you can’t even get them to do the motion capture. As you get older you’re not the same, your whole body language is different.

“And so, we had to cast specific actors to play them. And there was an audition process for all of that as well.”

As far as we're concerned, it’s time, effort and copious special effects money well spent.

Rogue One: A Star Wars story is in cinemas now