Receiving the script for Darkest Hour after working with Joe Wright on “Nosedive,” one of Black Mirror‘s most acclaimed episodes, editor Valerio Bonelli found more of a thriller than the straightforward period drama he was expecting, exploring ways to build tension through the cut and convey the stakes at hand during a critical turning point in World War II.

Examining Anthony McCarten’s script—which depicted Winston Churchill’s unexpected rise to the position of Prime Minister, and his battle against the Nazis— Bonelli realized that Darkest Hour wasn’t really a film about Churchill. On closer analysis, it was a film about 20 days in which the world could have become a much different place if one man didn’t stand by his convictions. Spending time on set and setting up shop in a house alongside Wright and his assistants, Bonelli worked with Wright in a way that felt refreshingly “old-fashioned,” as the pair watched rushes together every night, rather than alone on their respective devices.

In this sense, even amidst the world’s darkest hour, Bonelli found one of his brightest, experiencing an intimacy of collaboration that is now rare. Leaving no stone unturned, Bonelli would support the “House of Cards-type machinations” unfolding on screen by scrutinizing every line, and every space in between.

Jack English/Focus Features

What attracted you to Darkest Hour?

At first, I was very puzzled by the idea. I didn’t quite understand why Joe wanted to make a film on Churchill. Then he told me, “It’s Gary Oldman playing Churchill.” I said, “Ah, Going from Sid Vicious to Dracula to Churchill. That’s going to be amazing.” Joe started shooting in October 2016, and that’s when I started working on the film.

Being on set was a really unique experience. Me, Joe, my assistants, his assistants, and [cinematographer] Bruno Delbonnel—we all lived together. I set up my Avid downstairs in the living room. I would cut during the day and then at night, we would watch rushes together. We went back to our roots, and we were all on the same page. For me, being next to him on set meant that I got to understand what he liked and didn’t like early on, which was very important for me.

Jack English/Focus Features

As an editor, what does the experience of being on set offer you?

I don’t like hanging around on set too much because otherwise, I don’t get my job done. But if I know that they are shooting an exciting scene, I definitely want to go. It’s a way to get out of your hole sometimes. Sometimes, Joe would call me to discuss things, but most of the time I was cutting. We would see each other at night, and we would discuss the performance, how the film was taking shape.

What is the process when it comes to cutting the performance of an A-list performer like Gary Oldman?

I’ve been quite lucky so far, in that I’ve managed in the last five years to do films with Judi Dench and Meryl Streep and Gary Oldman. For me, Gary’s there in the Olympus of the great actors who transform and become the character.

As an editor, I can tell you that all the takes were good. But it’s noticing the progression of his performance from one take to another. I looked very carefully at all his takes. I knew that maybe at first, I would go for the one that looks the most perfect, which isn’t necessarily the last take—maybe among seven takes, it might be around Take 5 or 6. But when you watch the entire film and you maybe need to tone down a bit of some performance, you need to have the knowledge of, “Oh, there’s a take where he actually didn’t shout.”

There’s a scene in the film—the cabinet scene—where all these men are talking around the table. Those were the scenes where Joe asked me for help the most, in terms of creating tensions. What I really was keen to do was to find reactions from each character. I build timelines where I just cut reaction shots. Rather than going into rushes, I go into these selects of reactions as my way of finding material.

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I find that if you read a page of dialogue, you have dialogue, you have description, but the description is what actually changes because the dialogue is delivered. The actor can deliver it in one way or another, but my craft as an editor is to be able to fill the gaps between lines and create tension between one line and another. Those sequence are really built in the cutting, and that’s kind of where I had most fun.

In the dialogue, they’re discussing high matters, and the guys are all looking at each other like they’re playing poker, all challenging each other. Everyone’s keeping their cards in their own pockets. There’s a real sense of House of Cards-type machinations.

What is your process when it comes to refining the pace of a scene, and the rhythm of the overall film?

This not Joe’s taste, but I like tight films. I like long films, too, but I like a good pace. I actually always felt that the script had this element of this ticking clock that needed to be translated into the final film, this sense that the world could come to an end, or the invasion could come. How do you transport that feeling into the film?

A lot of people might see this story as a period drama, but I thought that the way Joe shot it, he wanted to create the sense of a thriller. In the cutting process, we worked in trying to create this pushing sense of a thriller. The last hour of the film is about four days in a row where Churchill has to make all theses decisions, so I was always pushing from my point of view to keep the film tight through those four days. I think by the end, we got there.

We did take out some sections of the film that on page, and even in the way he shot it, were very beautiful. We decided to keep the film economic in some of Churchill’s decision-making process—how to create Operation Dynamo, for instance.

Jack English/Focus Features

The sense of thriller was helped with the music, with sound. We worked with that very early on in the process. Dario [Marianelli, composer] gave me music from the first week of the shoot. The way Joe likes to work is that we never use temp music. We have Dario giving us themes. At the beginning, I cut with themes. Then, as the film goes along, the theme become more elaborate and orchestrated, and he gives me demos. The score grows organically. It’s a much better way of doing it.

How would you describe Joe’s approach on set? What was the shooting ratio?

Joe is a very precise director. He mostly shoots with one camera. The dialogue scenes, he shot with two cameras and I had a lot more footage, but otherwise, he’s one of these very precise directors that would do no more than 13, 15 setups a day, and would get those 15 setups really precise and really well executed.

I thought it was really interesting. I don’t have a preference, but you can decide to shoot a scene with three cameras and run it all, or you can decide to do it in one movement. Joe goes in between. I would say that I never felt under covered, really. There was always material to be able to manipulate the story in the cutting process.

Can you expand on those sequences that ended up being cut?

There’s a whole section in the middle where Churchill had the idea of calling Operation Dynamo, which involved him going around, being frustrated through the room, seeing people having fun in a birthday party, and then going to see this film with Laurence Olivier. In the end, they were all nice sequences, but they were kind of slowing down the film, so we took out a whole section in the middle.

Jack English/Focus Features

We really tightened the film, each scene. It was like fine-tuning, going into Gary’s performance and all the actors’ performances and finding the best moments. With almost every single cut, we said, “Okay, why are we doing this?” Joe’s very meticulous. I am too. It was an interesting process because I think I’ve never worked on a film where we only probably cut two or three scenes out from the start. The rest, we tightened up. We made sure that what is on the screen is the essential that is needed to tell the story.

Which were the toughest scenes to crack?

The first war cabinet sequence, for sure. That was like the longest dialogue scene ever, with lots of different emotions going through it.

But if there’s a whole strand of storyline that I was very keen to make work, it was the relationship between the King and Churchill. The first scene between Churchill and the King, when they meet, it’s almost the way it was cut during the assembly. It stayed like that, because it was perfectly shot.

But there’s three scenes between Churchill and the King, and for me, it was very important to get those three scenes right. We moved the position of the middle scene, which is the lunch scene, to another place from where it was scripted because we thought that it was better for the story to have it earlier.

Then, the last scene between Churchill and the King was very challenging because there was a lot of dialogue that we cut out. The way it was shot made it quite technically complicated for cutting. For me, it’s very important in a situation like this, where you have close-up shots where you see the back of the head of an actor—so you can’t quite manipulate the material as much as you want—to try and to make the cuts justified for the story, not just for technical reasons.

That scene was very tricky to cut because you had to convey several messages in that scene: You had to get Churchill out of the hole of his depression; the King to suddenly turn around and say, “I’m on your side.” Then, giving him a hint of how to solve his conundrum. The blocking of it was very complicated.