Just as Britain negotiates its inglorious retreat from Europe, and our political classes prepare to ratify the chaotic abandonment of a union intended to prevent another war, there seems to be a renewed appetite for movies about 1940. Christopher Nolan has given us his operatic immersion in Dunkirk, and now Joe Wright — who himself staged bravura Dunkirk scenes in his 2007 film Atonement — directs this undeniably exciting and beguiling account of Winston Churchill’s darkest hour in 1940, as Hitler’s forces gather across the Channel, poised to invade. It is written by Anthony McCarten, who scripted the recent Stephen Hawking biopic The Theory of Everything.

This is not so much a period war movie as a high-octane political thriller: May 1940 as House Of Cards, with the wartime Prime Minister up against a cabal of politicians who want to do him down. It’s interesting for a film to remind us that appeasement as an issue did not vanish the moment that Winston Churchill took over as Prime Minister; despite the famous David Low cartoon, not everyone was right behind him, rolling up their sleeves. Here, his immediate enemies do not seem to be Hitler and Mussolini as much as Chamberlain and Halifax, agitating for a deal with the Nazis and scheming to undermine Churchill’s cabinet and parliamentary position.

They are played respectively by Ronald Pickup and Stephen Dillane, the latter having a malign mandarin impassivity. Dillane makes him a pretty unholy fox. Ben Mendelsohn plays George VI, who is also an appeasement fan at first, though the film gallantly makes him a Churchill convert, conjuring a scene between the two of them in which his job is to stiffen Winston’s sinews. (This film incidentally doesn’t make the mistake in The King’s Speech of implying that Churchill sided with Bertie during the Abdication.)

Darkest Hour has obvious similarities to the recent film Churchill, with Brian Cox; like that drama it imagines a pretty young WAAF figure as his secretary, for him to be at first grumpy and then soppy with - Lily James plays this part here. Miranda Richardson played the exasperated wife Clemmie in the Brian Cox movie and here it’s Kristin Scott Thomas being exasperated and affectionate, helping the impossible old devil dress etc, in more or less the same way - although there’s more here for Scott Thomas to get her teeth into. But this movie packs a much bigger and more effective punch, and that’s down to a more ambitious scale, pacier narrative drive - and the lead performance.

Every time I sit down to another Churchill drama, I promise myself I won’t just roll over for another actor in the latex/Homburg/bowtie/cigar/padding combo and doing the jowl-quivering while speaking in thevoish and the weird cadencesh. And yet there’s no doubt about it, Gary Oldman is terrific as Churchill, conveying the babyishness of his oddly unlined face in repose, the slyness and manipulative good humour, and a weird deadness when he is overtaken with depression. There is a scene (a bit fancifully imagined) with Churchill slumped in a bleakly lit almost unfurnished room, where he looks like something by Lucian Freud. He spends a fair bit of time down in the bunker-ish Cabinet War Rooms yelling at people: these are the “Upfall” scenes, which might get YouTube-subtitled in German in all sorts of irreverent ways. And it is here that Winston reaches his nadir, before the miracle of the little boats has manifested itself. He allows Halifax to send word via the Italians that Britain would be theoretically interested in the Danegeld-price: what might induce Hitler to hold back from Britain and its colonies? Oldman shows Churchill going into a kind of stricken shock.

This is not to say that there isn’t a fair bit of hokum and romantic invention. This film imagines Churchill needing to take a journey on the tube because his official car is held up in traffic. So he meets a quaint cross-section of forelock-tugging British and empire subjects in the underground carriage, from whom he learns something very important — that he is absolutely right!

There is room for a more sceptical movie about Churchill: something revisiting his performance during the Tonypandy Riots or the Siege Of Sidney Street. Or just something that acknowledges that he hated Adolf Hitler for the same reason he hated Mahatma Gandhi: they were both enemies of the British Empire. But Gary Oldman carries off a tremendous performance here, and it’s impossible not to enjoy it. It’s as if his establishment panjandrum George Smiley was suddenly infused with the spirit of Sid Vicious.

