Geoff Bar­row and Ben Sal­is­bury on their Free Fire soundtrack

Fol­low­ing their recent sci-fi infused exploits on Ex-Machi­na and Black Mir­ror, com­posers Geoff Bar­row and Ben Sal­is­bury have toyed with an alto­geth­er dif­fer­ent sound for their lat­est work, the ​’70s-inspired score for­Ben Wheatley’s Free Fire.

Bar­row and Wheatley’s pre­vi­ous col­lab­o­ra­tion on High-Rise saw Barrow’s band Por­tishead con­tribute a mem­o­rably haunt­ing cov­er of Abba’s ​‘S.O.S.’, while Free Fire’s sim­i­lar peri­od set­ting rep­re­sent­ed an oppor­tu­ni­ty for Bar­row and Sal­is­bury to explore the jazz­i­er sounds asso­ci­at­ed with action thrillers of yesteryear.

We sat down for a chat with the duo to find out how they wrote their sparse, eclec­tic sound­track, which makes for the per­fect accom­pa­ni­ment to Wheatley’s dis­tinct brand of trig­ger-hap­py carnage.

Sal­is­bury: I think it was through ​‘DROKK’ [the not-quite-sound­track album made from mate­r­i­al intend­ed for use in Dredd, which ulti­mate­ly went unused when Bar­row and Sal­is­bury left the project]. Ben wrote a tweet say­ing that he’d love to see a film with that as the sound­track. Then Ben saw Por­tishead, and after one live ​‘DROKK’ gig we watched Sight­seers, so it was sort of coin­ci­dence. Around the same time he got in touch through Twitter.

BS: The script was right up our street as were all the musi­cal influ­ences we talked about – The Dri­ver, Escape from Alca­traz, The Tak­ing of Pel­ham One Two Three – all those big brassy ​’70s scores. So we wrote a cou­ple of big brassy ​’70s-style themes and Ben loved them. It was only when we turned up on set… Ben does this thing where he lit­er­al­ly gets an edit as he’s going. He has this very rough edit at the end of each day, and he put some of our music on it and we sort of looked at each oth­er and, even then, we thought, ​‘I don’t know if this is right now’.

GB: It felt like it kind of worked, but when we saw the colour palette and the real­ness of the mid-’70s set­ting and the char­ac­ters, we realised it was far too cool. That music can be quite hero­ic and intel­li­gent and it was absolute­ly the oppo­site of that. The char­ac­ters in the film are absolute idiots, real­ly. We need­ed to write some ​‘idiot music’.

BS: There’s a chance that one of those tracks might come out as a bonus track on the sound­track. If not, we’ll have it up our sleeves if any­one comes to us want­i­ng a big brassy ​’70s theme.

BS: Obvi­ous­ly there are sup­port­ing tracks, like the John Den­ver track ​‘Annie’s Song’, but the idea was to have ​‘bought-in’ tracks that suit­ed the char­ac­ters. And the fun­ny thing is you don’t have to be mas­sive­ly timescale spe­cif­ic. In the same way that the cos­tume design reflects what the char­ac­ters would wear, the music is what the char­ac­ters might lis­ten to. And that, actu­al­ly, could be any­thing from the ​’70s. Who knows what Michael Smiley’s char­ac­ter would have been lis­ten­ing to? When [exec­u­tive pro­duc­er] Mar­tin Scors­ese saw the film for the first time, he said, ​‘Ben, I love the music you’ve found,’ and Ben said, ​‘Oh, no – that’s actu­al­ly been writ­ten.’ That was the best com­pli­ment we could have had.

GB: We end­ed up going down a pub prog kind of route. We were influ­enced by bands like Mag­ma or Camel, and because of where the char­ac­ters came from, it just end­ed up being a Belfast pub band.

BS: The oth­er wink to that is there’s quite a lot of clas­si­cal gui­tar in there, which also was a big thing in prog around then – that sort of pre­ten­sion to pseu­do-clas­si­cal grandeur.

GB: That’s prob­a­bly Vern, isn’t it? A South African drug deal­er who lis­tens to pseu­do-clas­si­cal music. You can imag­ine him invit­ing some poor young woman round to his pad to lis­ten to that…

BS: We felt like we were the film’s in-house band.

GB: It was Ben’s idea for us to do a cov­er of ​‘S.O.S.’. Clint [Mansell] had done ver­sions of it, so we got togeth­er and did it and it worked out. I think he actu­al­ly con­tact­ed Abba and, ran­dom­ly, it turned out they were fans of Por­tishead, which is total­ly bril­liant. We nev­er released it because, to be hon­est, we didn’t want it to be released. We made it for the film and I don’t think, as a track, it works out­side of that. I don’t know if Abba have actu­al­ly heard it. I’m sure they have, to give it clear­ance. You can do cov­er ver­sions, but if you mess around with the arrange­ment that’s when the band can get involved, or you change a lyric or you change a cer­tain amount of bars. If some­one does an awful cov­er ver­sion, you can get them to change it, or not do it at all. But if they cov­er it immac­u­late­ly in all bar lengths or notes, the artist has no say. We’ve stopped so many atro­cious Por­tishead cov­ers. And we’ve had stuff come through that we haven’t been able to stop which we’ve des­per­ate­ly want­ed to.

BS: I def­i­nite­ly couldn’t pick one.

GB: I’ll choose two, if I’m allowed two: Assault on Precinct 13 and The Good, The Bad and The Ugly.

BS: It depends on where my head’s at, but the things I go back to and lis­ten to are Jer­ry Goldsmith’s Plan­et of the Apes, Bernard Herrmann’s Psy­cho, and stuff that influ­enced me as a kid. That’s prob­a­bly the most hon­est answer, it’s what­ev­er has stuck with me and still gives me goose­bumps, John Williams’ stuff. The theme from Star Wars still gets me.

Free Fire is in cin­e­mas 31 March. Geoff Bar­row and Ben Salisbury’s sound­track will be avail­able soon via Inva­da Records.