England, 1944: After 5 long years of blitz, black-out, rationing and requisitioning, the World War hit hard on the Home Front. 'A Canterbury Tale' is a British wartime film appealing directly to the newly-arrived American allies to regard the sight of an English Cathedral spire, an old pilgrim road or clear skies over chalky uplands as worth fighting to preserve. A victory for our enemies, it seems to say, would mean an end to this spiritual continuity, and the heavy burden of defending it had fallen to us and our Comrades. Thus the film can be taken on one level as a straight-forward flag-waver.

But it is clearly more than this. The opening of the film, quoting loosely from Geoffrey Chaucer, depicts a medieval pilgrimage, the old Canterbury Pilgrims journeying to receive blessings or do penance. Fast-forward to wartime, and a different kind of pilgrim walks the way. Our boys are massing in the South to embark on the great mechanized Crusade that will determine the future of England and all that it stands for. Their task is an onerous one. But what's this? Girls out with soldiers in rural Kent get glue poured in their hair at night. What can it mean?

Powell and Pressburger take their time in spinning their story, but it's time we don't mind spending in Chillingbourne, wending our way with Alison and the farm cart, blackberrying on the Weald with Peter and Bob, chewing the fat with the locals, getting to know our pilgrims' histories and ultimately solving the Glue Man crimes. There are many meandering diversions along this particular road, and some bits of business are downright peculiar (the silhouetted village idiot scene and the young boys' play-fight spring to mind). But by degrees, the film's narrative themes begin to coalesce, and slowly we are taken somewhere very special indeed.

It's true, Thomas Colpeper - gentleman farmer and magistrate - is something of an oddity, but no small town is complete without its eccentric. There's a magnetic and sympathetic quality about him, too, as we see when Alison bitterly comments on her prospective In-Laws' refusal to accept she's good enough for their son: 'It would take an earthquake' she says, to which Colpeper calmly replies, 'We're having one.' As played by Eric Portman, he is at once coolly beguiling and strangely malevolent. His unmasking by our protagonists as the 'Glue Man' comes as no real surprise, but seemingly his motivation is only about assuring our connection with the land and its history, despite being himself irredeemably misogynistic to our modern eyes.

The final act, as the foursome complete their pilgrimages to Canterbury on the iron road, is a revelation; As they, and we, are propelled closer to the imposing Cathedral, the characters' stories are completed: Colpeper is set to do penance by turning himself in to the Police, Peter is told he was the instrument for this but instead gets a blessing of his own, Bob finally receives his girl's letters, (posted from Australia, "She's joined the WACs!"), and Alison is similarly blessed. Her scene in Mr Portal's Garage is especially moving, as the burden she carries is the hardest - the presumed death of her airman fiancé. Her barely-audible 'Why?' whispered in disbelief when told Master Geoffrey's father has waited with news for her for two weeks delivers a moving emotional payoff. Sheila Sim - now Lady Attenborough - gives a memorably natural performance throughout.

The film's luminous black and white photography is strong as is the location work in and around the recently-bombed Canterbury, and the use of music throughout adds a spiritual element to the visuals. My Favourite scene? The steam-hauled commuter train bearing our pilgrims from Chillingbourne pulls into Canterbury station, and Peter stands in the compartment to adjust his uniform collar. Apparently he's been the unwitting but skeptical instrument of Colpeper's penance, and his line 'I'll believe that when I see a halo around my head,' comes as the carriage window behind him is suddenly bathed in blinding morning sunlight. Brilliant.