But what was it that made Wheatley believe there was a movie in these characters?
"There was a couple of things. I knew Alice and Steve, and I fancied doing something that had a lot of improvisation in it. There was improvisation in my other films, but not as much as there was in Sightseers. And also when I read the script it kind of fitted with the other two movies I've made - it had elements that made sense to me. Then we took that script to [Wheatley's wife and collaborator] Amy Jump and we tailored it to suit the other movies a bit more."
Although Wheatley was involved in the development of the script, it is his first film for which he does not have a screenplay credit.
"It's a different thing working with writer/performers where you can't ride as rough shot over the production of it as you can with your own stuff. The other movies I could just go 'I'll scrub this'. But the shoot itself was very loose, so it felt very creative. It didn't feel like I was being held back."
Was he looking for something lighter to do after the bleak Kill List?
"Totally yeah. I committed to Sightseers before I made Kill List but I kind of knew that Kill List was gonna be so dark. It was a gift being able to jump genres like that and make a lighter film after making a horror. It would've been easy to have done another horror film right on the heels of Kill List, but I could've got myself in a position where I could only make certain kinds of movies or I would only be offered certain kinds of films. And I was conscious of that. I want to be able to make all different types of movies so I don't want to pigeonhole myself too much."
The humour in Sightseers is jet black, and balances on a fine line. I asked Wheatley if the funny moments came together more in the editing room or on set.
"A bit of both really. The script was pretty tight so we always went back to that. It was more about trying to get the improv stuff - which was funny but wild - to fit with the rest of the story. We used the same techniques we used on Kill List and [Wheatley's first film] Down Terrace which was to do an off-script version, then go back on-script, then another off-script version. That seemed to go pretty well for loosening everybody up. Plus if we found something at the locations we might go and shoot a little bit of improv. Then in the edit we'd see if we could put it all back together again. Sometimes the extra bits we shot became the scene and we dumped the scripted version. So there was all sorts of different ways of working it."
There's an almost Larry David-esque quality to the manner in which Chris gets riled-up by the minor offences of his victims. I was keen to see if Wheatley related to Chris's frustrations.
"Yeah totally. The whole thing is this idea of taking these things to their logical extreme. People talk as if they wanna do these things, but when you're confronted with the reality, the madness of it, it's a terrible thing that you've done. And the crime that they've committed is outweighed by the crime you've committed. The moral feedback is horrific. Also, he doesn't really have much of a moral code. Nobody really deserves do die."
That's good to know! Some pretty violent acts occur within Sightseers blackly comic context, and Kill List was notoriously brutal. Does Wheatley have a particular philosophy when it comes to onscreen violence?
"A philosophy? I dunno. I know what I like to see in films and I don't like to see people pull punches when they're showing violence because it's disingenuous. You want to see that reality of it. Otherwise it's kind of saying that the violence isn't real, that people don't actually get hurt when they get hit. And I think that's a bit odd. It's more about tone than anything - the violence in Kill List and the violence in Sightseers are different because of the tones. It's not as uncomfortable in Sightseers. It wasn't for me anyway. I found the violence in Kill List very uncomfortable."
Never one to rest on his laurels, Wheatley has just finished shooting his enigmatic next film - A Field In England. The IMDb lists the project as a horror - I asked Wheatley if that's correct.
"I dunno. I think that would be a stretch. It's 'psychadelic period'. It's set in the English Civil War. It's soldiers running away from a battle who end up crossing over a mushroom circle into a magical field. Then they all go insane. And it's black and white aswell. I don't think I'll ever get offered any other psychdelic war movies."
Sounds awesome! Following that is Wheatley's most ambitious movie to date, so-called 'monster movie' Freak Shift.
"Yeah we're working on that in the moment, and we'll hopefully shoot in April. It's a big budget thing so it's much more complicated to get it together than the other movies. We've written this one. It's Hill Street Blues versus monsters."
On board!
Check back here on Friday for the second part of my Ben Wheatley interview, in which he talks to me in detail about one of my favourite movies of the last ten years - Kill List.