A Matter of Life and Death is the utterly unique, enduringly rich and strange romantic fantasia from Michael Powell and Emeric Pressburger. You could put it in a double bill with It’s a Wonderful Life or The Wizard of Oz, though its pure English differentness would shine through. It was released in 1946, the same year that Winston Churchill coined the term “special relationship” – an idea that the film finds itself debating. With that concept now under pressure, 2017 is a good time for this classic to be rereleased in UK cinemas.

The film begins with a sensational flourish: a nuclear explosion that destroys a solar system. We start by drifting through outer space, accompanied by a droll narrative voice, commenting on its vastness and noticing a sudden supernova way in the distance: “Someone must have been messing about with the uranium atom.” The eerie casualness of that revelation sets the otherworldly tone for the rest of what follows. The starlit expanse, the intertitles, the distant detonation, the huge quasi-senatorial valhalla, all hint at where George Lucas got ideas for the Star Wars movies.

Then we find ourselves on Earth in 1945, where RAF pilot Peter Carter, played by David Niven, is flying back to Britain after a bombing raid, losing height, badly hit. He has presumably been attacking German cities, and it has to be noticed that Germans are not represented here, either in this world, or the next. Carter’s parachute has been damaged; he knows he is going to die, and with impossibly dashing flair, he radios his final position to an astonished American radio operator called June, played by Kim Hunter, asks her to contact his family and flirts with her. June and Peter fall in love at that moment.

The miracle is that Peter seems to survive, staggering out of the sea. He finds June, and with the help of a local doctor, Frank Reeves, played by the incomparable Powell/Pressburger stalwart Roger Livesey, he is gradually nursed back to health. Yet an emissary from heaven, in the form of a dandified pre-revolutionary French aristocrat played by Marius Goring, informs Peter that his survival is a mere clerical error and he is expected back in the afterlife right away. Peter complains that now he has fallen in love he is entitled to remain below. A huge trial is in prospect, and a prosecuting counsel is chosen: American revolutionary veteran Abraham Farlan (Raymond Massey), who intends to argue that this decadent Brit has no business with a good American girl. Frank believes that these heavenly visions are delusions caused by his brain injury and everything – or almost everything – is consistent with that rational explanation. But how did Peter survive the fall?

A Matter of Life and Death is a visually extraordinary film: a gorgeous artificiality is created by Alfred Junge’s production design and Jack Cardiff’s vivid Technicolor photography. Counterintuitively, the heaven scenes are in black and white and Earth is in colour. The modernist architecture of heaven is something to rival Fritz Lang’s Metropolis and the “stairway to heaven” sequence (which gave this film its US title) is narcotically weird. Even down on Earth, and without the angelic visits, things have a distinct surreality. Frank likes nothing more than to keep the village under benign surveillance with his camera obscura device, evidently kept on a high rotating turret, which gives him live pictures of everything that’s happening in the village. He is like the voice and eye of an all-seeing God. And perhaps the most extraordinary moment comes when Peter encounters a naked young goatherd on the beach: it is this figure – like someone from a late Shakespeare play, such as The Tempest – who tells Peter that he is back on Earth. (The boy’s nakedness meant that this sequence was cut for TV transmission by prim US networks; Martin Scorsese has spoken entertainingly of his periodic exasperation at sitting down to watch and finding it is the bowdlerised version.)

So what does this film have to say about the special relationship? The speechifying on the subject of history and politics might disconcert some viewers who would rather hear and see more about Peter and June’s romantic adventure. But Powell and Pressburger are telling America and the world that just as Squadron Leader Peter Carter does not want go to heaven, so Britain itself is not dead; it does not deserve to be consigned to history along with those effete and irrelevant periwigged Frenchmen. Britain lives – in partnership with America.

I have watched this film many times, but it was only on sitting down to it again that I finally realised what Frank Reeves’s death reminded me of. Riding his motorbike fast in the rain, Dr Reeves had selflessly swerved in order to save the lives of the ambulancemen and their patient, conveying Peter to hospital. His sacrifice means that he can go to heaven to be Peter’s defending counsel. How should we feel about this terrible event? I had a flashback to a long-suppressed memory of reading CS Lewis’s The Last Battle, the final Narnia episode, in which Peter, Edmund, Lucy, Diggory and Polly are revealed to be killed in a train crash, along with the Pevensie parents, and so they can be admitted to eternal life. It was a profoundly strange happy-sad collision. So is this.

• This article was amended on 8 December 2017. An earlier version referred to Peter Carter as an “RAF Hurricane pilot”, and in the subheading as a “fighter pilot”. He piloted a Lancaster bomber.