How did you get into directing for television and was it a long-held ambition?
I started out in editing. As an assistant editor I could observe some brilliant directors in the cutting room. That was a great learning experience. Then when I made the grade as an editor, I found my opinions rapidly getting stronger and stronger, analysing what my directors were doing, thinking how I would have shot it. I suspect I might have been quite an opinionated editor! At that point I knew I had to direct.

You directed two gorgeous-looking episodes of Doctor Who in 2015 (The Girl Who Died and The Woman Who Lived). Coming into such a long-running series and working with a large team, how do you put your personal stamp on a production?
Doctor Who has such enduring appeal, it’s a global phenomenon. And yet part of its strength is that each episode is treated as a standalone film – it feels more like making a one-off. So every director has the chance to put their own mark on the series.

We had so much fun making those episodes, and despite there being a character through-line they couldn’t have been more different. We had to create a Viking world, design the Mire and introduce Maisie Williams to the series. Turn that round in two-and-a-half weeks then make a 17th-century period piece that was a highwaywoman romp, a dark reflection on immortality, topped off with an alien space attack at a Tyburn hanging, all wrapped up in an homage to Gainsborough Studios.

Each director is brought in for their track record and encouraged to play to their strengths – I had a clear sense of what I wanted to do with each script and you’re so well supported by the incredible team they have in Cardiff. “Incredible team” – that may sound a bit glib but they really are extraordinary. From the people booking transport and running the office through to your producer, you’re surrounded by people who have this depth of knowledge and passion for Doctor Who – it’s almost humbling – and they’re all there to help you realise your vision. With friends like that, putting your own stamp on a production is definitely easier…

What were your first thoughts when you received Steven Moffat’s script to The Return of Doctor Mysterio?
Erm… I can’t put this down, this is great and OK, how are we going to make this?

From the first draft it barely changed – it was tight, compelling and funny. And the sense of threat was real.

Then you start to think of the logistics – a superhero who flies… over New York… we’ll need New York streets… New York apartments… Then the finer detail: Hayley Nebauer, our costume designer, pointed out that the average lead-time to design a new superhero costume is six months minimum. By then we had a little less than a month. Then you get into deeper discussions – cape or no cape – it was like that scene from The Incredibles! We decided the cape stays in the picture. Then the granular detail: what weight material for optimum cape performance in flight? A runner volunteered to flight-test the different weights – we created our own wind tunnel in the studio. Two hours later we’d agreed on the weight for the cape fabric. One small step, but as they say, the devil is in the detail.

Were you a superhero fan as a boy and which classic movies, if any, did you study for inspiration?
I remember going to see Christopher Reeve’s Superman. That was a Christmas release too. There was a big buzz around the film and it didn’t disappoint. Going back even further – guilty pleasure time – Adam West’s Batman left a big impression. Irreverent, camp, funny and dark too, and possibly the second-best theme tune of all time. Watching Sam Raimi’s Spider-Man films with my sons when they were tiny – that was a key inspiration for Doctor Mysterio, particularly the rapport between Tobey Maguire’s Peter Parker and Kirsten Dunst’s MJ. I wanted the film to evoke those memories. And Steven was clear he wanted to go back to a superhero style that was full of wit and fun, when ingenuity was in the script and the camera and didn’t all occur in computer-generated effects. I was also fascinated by the small everyday details in those films, the apartments, the streets, the backgrounds. No matter how fantastic the film, finding the reality is vital. On the subject of Spider-Man, there are some Easter eggs dotted around Doctor Mysterio: look out for a certain pizza parlour.

What’s been the greatest challenge making this Doctor Who Christmas special?
There were so many – the Doctor’s first appearance in the story probably consumed the most discussion time but we were so clear from Steven’s script how we wanted to shoot it. It was the first scene I storyboarded. Once we had the visuals, it was hours and hours of me, Peter Bennett (producer) and Fletcher Rodley (assistant director) painstakingly going through each shot, breaking it all down and working out a methodology for each shot. Often complex sequences evolve from the initial plan – but in this instance the finished sequence is very close to those original storyboards.

From the start we knew we wanted a neighbourhood New York feel for the area around Lucy’s apartment: real streets, a subway, big yellow taxis, everything. We also knew we didn’t have the time or money to shoot in New York. Amazingly, there’s a studio just outside Sofia that had exactly what we were looking for. We were there for the briefest of moments but you believe you’re in New York.

How were the flying shots achieved, especially when the Doctor is zooming along with the eight-year-old Grant?
We shot some of the flying scenes suspending the actors on wires, which is the traditional way, but for most of the flying we tried to keep it much simpler. We had a contraption that we called the seesaw, which was basically, well, a seesaw. The flying shot of the Doctor and young Grant was simplicity itself. We had two boards like small ironing boards – Logan (Grant) lying on his front, the Doctor lying on his back. They stayed in one position and we moved the camera around them. Outrageously simple!

How did you feel when you saw the finished version with all the music and effects on the big screen at the BFI?
Who doesn’t enjoy seeing their work on the big screen? It was emotional! You’ve been wrapped up in something for months, immersed in the detail, it’s all-consuming. Then suddenly it’s out there in front of a huge audience. I sat at the back because I wanted to see how the audience were reacting. I was watching them as much as the film. It looked great, and the audience was incredible, it was so good to see the gags landing. And there’s so much detail that you experience with greater clarity in the cinema and not just visually. Hearing both the power and the nuance in the sound design was so good – something that can be easily missed on TV.

You directed the opening episodes of Endeavour, Poldark and Doctor Who spin-off Class. What particular challenges or freedoms are there for a director in getting a brand-new series off the ground?
In directing opening episodes, you get to set the look and tone of a new series. Like everything in TV it’s a collaborative process but you’re right in the middle of it all – it’s a lot more responsibility but allows you more creative licence. Of course the process is different in each instance and the key for me is finding my own entry point into the story. Once you find that, things start to flow. With Poldark, it was seeing the landscape as a character: understanding how the wild and unpredictable nature of Cornwall – the climate, the terrain, the sea – had informed the way Winston Graham had created his characters in the novels and seeing how Debbie Horsfield had threaded that idea through her scripts. Once I had that, so much fell into place – I loved all the jokes about “there goes Ross, galloping off on his horse…again”. It kept the sense of place front and centre throughout those opening episodes where we were establishing our world.

And coming in at the start gives you the opportunity to spend more time with the writer. Debbie Horsfield on Poldark, Patrick Ness on Class, Russell Lewis on Endeavour, Chris Lang on A Mother’s Son – I’ve worked with some great writers and they’ve all been really collaborative. And despite having so many projects to juggle, Steven was always available to work through the Christmas script. That time spent together and those conversations gave me so much more depth and detail: it was invaluable.

You are also pivotal in the casting, one of the best parts of the process. You’re at the start of prep, a million decisions to be made – there’s so much on your plate. But hearing the script come to life, each actor bringing their own interpretation, interrogating each line, never fails to inspire me. It’s like shining light on a brilliant diamond, constantly seeing the script from a fresh angle, in a new light. You get this real sense of momentum building. It’s thrilling.

Directing Poldark series one, you were responsible for Aidan Turner’s famous topless scything scene, which put many of our readers, and the ladies in our office, into a lather. Anything you’d like to say about that?
Ha! I love it when a plan comes together! Debbie had written this wonderfully sensuous scene: she describes Demelza watching Ross from a distance, hidden in the long grass, seeing her boss very differently after the events of the previous night – so it was all Demelza’s point of view! This scene that came to define Poldark, that got everyone talking about Aidan, was actually written from Demelza’s perspective.

What is your next project and if you have another stab at Doctor Who, what would you like to direct?
A break! We were working on the VFX for the Christmas special right up to the BFI screening and it’s been a hectic year so the next project is a few weeks off! After that there’s a great Cold War story that I’d love to make, and a couple of other projects to consider.

I would love to do more Doctor Who. What I would like to direct and haven’t done yet is something truly dark and scary. Before my first episode I was talking to my teenage son about his Doctor Who memories. His most vivid recollection was The Empty Child [2005] – it scared the life out of him when he first saw it. We watched it again together, and were terrified a second time. That, and the following episode The Doctor Dances, were amazing scripts with all my favourite elements – the recent past, a beautifully realised world, grounded in reality, a powerfully emotional story with a heart of darkness. If something as good as that came up again, I’d walk back to Cardiff to direct it…