Since the film was shot on a clockwork Bolex camera, sound couldn't be recorded on location. All the dialogue and sound effects were then dubbed in post.
Much of the film was shot in the Admiral Benbow, Penzance. This pub, opened in 1959, houses thousands of artefacts salvaged from ships wrecked of the Cornish coast and the Isles of Scilly.
Director Mark Jenkin processed the 130 rolls of Kodak 16mm B&W film 16mm film himself in his studio.
In a 2019 interview with Film Comment, Mark Jenkin detailed his shooting technique and process: "I shoot with a manual clockwork Bolex 16mm camera, and I have to physically hold the shutter down. I've got two choices for what I can do with the other hand: I can either pan or tilt the camera, or I can focus pull. So this aesthetic was borne out of what I could do with that camera, and its limitations. A lot of the close-up work is something I always do because I don't shoot any coverage. I always shoot feet to cover myself for transitions, but you can also tell a lot about the characters by looking at what shoes they're wearing and what their feet are doing. You've got this stark contrast between leisure and industry that runs through the film: delicate shoes or trainers are always up against working boots. Hands as well. The working hand. The blue-collar and the white-collar hand, effectively. You can say so much more with an image rather than any expositional dialogue. Whether I'm reverse-engineering meaning into those shots, or whether that was always there and I just wasn't conscious of it, it's still really important to me.
The really key thing is that I shoot 100-foot rolls of film, so I load everything into the camera when we're out and about filming, so the beginning of each roll is flooded with daylight. To get to the point where it's usable, I normally fire off a few feet of film of whatever's nearby, so I end up with a random close-up. In the edit, I know it will have some relevance because it's there in the scene; it's part of that place, or it's part of that person. An example of that is in the pub, where you've got the figureheads and the busts from all the maritime ships. I didn't even see any of those carvings when we recced [scouted] the location. It wasn't until I was set up for a dialogue shot that I thought, 'Right, I've got a few feet to fire off, what can I shoot? Let's spin the camera 'round.' There'd be a carved woman's face staring at me, and suddenly, that's now in the edit, and quite a big part of those scenes. So a lot of it's borne out of those limitations. If I was shooting digitally and I didn't have those constraints, I never would have considered those close-ups, those cutaways."