“Did you know that weathermen are traditionally boring?” asks a kindly Irish secretary in Pressure, about the real-life wartime meteorologist James Stagg. It’s a problem that director Anthony Maras, in adapting David Haig’s 2014 stage play, valiantly tackles head on. How do you make nerdy militarians talking, studying and map-reading in a time of crisis feel particularly cinematic? The answer is you keep it tight – Pressure is, blessedly, a lean 100 minutes – and you hire an actor with one of those great listening faces, whose moistened eyes and tight jaw can make even the stuffiest of scenes feel suddenly bright and alive.That actor is Andrew Scott, offering an amuse-bouche before his Oscar-tipped role as the late stage star Ian Charleson in Elsinore in January. He is Stagg, whose sterling reputation in political circles saw him recruited to predict the weather ahead of the Normandy landings. His chilly, by-the-book respect for data – however unhelpful it seems to the more gung-ho Americans – sees him clash with many of his new colleagues, particularly Damian Lewis in full moustache-twirling mode as General Bernard Montgomery, and a hammy Brendan Fraser as then-US Army General Dwight Eisenhower.Stagg insists Eisenhower hold off from launching D-Day as perilous storms are on the horizon, even though – as Eisenhower points out – it’s sunny outside as they speak. But Stagg is insistent. Invade too early and military ships will be faced with enormous sea waves and poor visibility. Invade too late and we’re toast anyway. Dramatically speaking, this is all a bit more interesting in theory than in practice, Maras’s film largely confined to a series of identikit studies and war rooms. Venturing outside of it doesn’t help much, either, with the eventual recreation of the D-Day landings themselves sparking unflattering comparisons to Saving Private Ryan, budget constraints on full display.Andrew Scott in ‘Pressure’ (Alex Bailey/Focus Features)Thank goodness, then, for Scott, who plays Stagg as an intriguingly stone-faced luddite who seems to be the only person to recognise the true gravity of war and violence. He nicely underplays it all, his expression one of quiet unease and very British dignity. There’s a bit of entirely invented drama at the film’s midpoint involving Stagg’s pregnant wife, which in any other actor’s hands could read as deeply silly. But Scott is so captivating in this particular moment – in which he is told of potentially horrifying news over the phone by an eerily chipper emissary – that it leaves a lump in your throat. Great stage actors, like Scott, have a tendency to go big on screen, but he’s a rare sort: someone who recognises that the camera can pick up on tiny, powerful facial cues in ways that are totally lost in a theatre. It’s a very special performance in a very ordinary film.Dir: Anthony Maras. Starring: Andrew Scott, Brendan Fraser, Damian Lewis, Kerry Condon, Chris Messina. Cert 12A, 110 minutes.‘Pressure’ is in cinemas