If you only see one puppet-based, all-star World War II comedy epic at this year’s EIFF, it surely has to be Jackboots on Whitehall, the long-gestated project of the McHenry brothers, Ed and Rory. Set in an alternative universe where Nazis have successfully invaded Great Britain, Jackboots features Ewan McGregor as Chris, a big-hearted, big-handed soldier who fights back against the invasion with the aid of the bravest of all the Brits, the Scots. But bringing Jackboots to the screen did entail a few casualties along the way …

‘It’s sad to say, but yes, some puppets were harmed in the making on Jackboots on Whitehall,’ says Ed McHenry. ‘In fact, many, many puppets were harmed during the filming. On the first day, we had a puppet which was meant to be flying a Spitfire, and unfortunately he kept catching fire himself due to the heat. We ended up having fans positioned all round the set to keep the puppets cool.’

Featuring Alan Cumming as Hitler, Tom Wilkinson as Goebbels, Richard Griffith as Goering and Rocky Horror star Richard O’Brien as Himmler, Jackboots on Whitehall clearly isn’t the place to look for a history lesson. For the McHenrys, their aim was to present a satirical fantasy aimed somewhere between Team America and Dr Strangelove.

‘We used to play with GI Joe puppets in the garden, and we’d made three low-budget films with puppets before this, but we never imagined that we’d be doing it again on this scale,’ says Rory McHenry. ‘We wanted to create a big, epic narrative on a Star Wars scale, and the joke is that we filmed it in this very small-scale way, 1.6 scale to be exact. The humour isn’t the same as Team America, where there are lots of jokes about the puppets swearing and saying sexual stuff; we’re aiming for something more innocent, like a mixture of Spike Milligan and Monty Python.’

‘When we were preparing, we watched classic films like It Happened Here, which also features an alternative universe Nazi government in the UK, and Peter Watkins’ The War Game; we wanted to get exactly the right, serious tone. And there’s also a retro style in Jackboots that harks back to the days of Powell and Pressburger; even the title is designed to evoke memories of Ealing comedies like Passport to Pimlico,’ says Ed McHenry. ‘We also took things from classic British films, like using scenes from Brief Encounter as the inspiration for Chris’s relationship with our English rose Daisy [Rosamund Pike].’

English roses are all very well, but EIFF audiences are likely to be pleased to see the plucky Scots riding to the rescue, and saving the bacon of our brothers down south.

‘I don’t want to give too much away about where the story goes, ‘says Ed McHenry. ‘But yes, the Scots are very much the cavalry riding to the rescue, so it’s a nice twist of fate that audiences at the Edinburgh International Film Festival will get to see the film first. I hope they enjoy it.’