It's 1940 on the western seaboard of the continent of Europe. The retreating British army is driven back to the sea on the beaches of Dunkirk, and makes good its escape back to England carried by a makeshift fleet of sea-going pleasurecraft and small boats that previously carried parties of holidaymakers up and down the Thames or over and back to the Isle of Wight. But his time the advancing German army does not stop at the coast.....

The premise of this most unusual war film is that Britain was invaded and occupied after the Dunkirk retreat, and in a mixture of documentary and narrative styles it sets out to tell the story of the occupation that the country narrowly (some would say, unaccountably) escaped, up to and including the 'liberation', orchestrated by the efforts of local partisans with American assistance, in the war's closing year.

This is a low-key, reflective war drama, which follows its central character, an Irish- born district nurse working in a village near Salisbury, through the horrors of a partisan ambush that goes wrong, to a chilling Nazi-dominated vision of London, where she finds herself assimilated into the highly political "Immediate Action Organization" and receives her "political re-education", on to a rural medical centre specializing in euthanasia for "undesirables", through to the final chilling irony of "liberation" and the wholesale slaughter of "collaborators".

It is hard to believe that this film began its life as the spare-time project of 18-year-old Kevin Brownlow, a film enthusiast working in the cutting-room of a small London production company, and his 16-year-old schoolboy friend Andrew Mollo, who had a passion for military history and a collection of old German uniforms and regalia. Starting without a budget, using a borrowed 16 mm camera, the two doggedly pursued their dream of completing the project for almost eight years, finding actors, actresses, sets and backing as they went along. The incredible story of the film's birth is told in Kevin Brownlow's 1968 book "How It Happened Here" (Doubleday & Co., New York), now unfortunately out of print.

The most famous sequence in the work is a six-minute scene in which genuine Neo- Nazis expound their ideas. When the film was first previewed at various British film festivals, it was this scene that incurred the wrath of a number of Jewish organizations, who maintained that the film lacked balance in that no substantial counter-argument was presented to the opinions expressed by these monsters. Early performances were greeted by jeers, chants of "shame" and mass walk-outs from film theatres.

Kevin Brownlow maintained throughout that the Neo-Nazis condemned themselves out of their own mouths for anyone with an ounce of intelligence, but the topic was too hot to handle and in order to get the film accepted for distribution by United Artists the Directors had to agree to the removal of the sequence, which was not allowed back into the British release version until the distribution rights were taken over by Connoisseur in 1993. The Connoisseur video version of that date is a full, uncut transcription.

As well as the Jews, many others were offended by the film, and it was widely criticized on political grounds, as being deeply unpatriotic. The British public had been flattered by Churchillian rhetoric into believing itself exempt from the flaws of other national groups. A people who had become accustomed to declaring: "Thank you, Lord, that I am not as other men!" was being tapped in the shoulder and told: "Sorry, my friend, you are no different". There could be no more subversive artistic act than an attack on this smug self-image. Every individual and every group that the film portrays is tainted in some way with moral compromise. We are presented with an England peopled by cowed and unthinking conformists who just want to "get the country back on its feet"; fanatical resistance fighters who have no concern for the fate of ordinary people caught in the cross-fire; German soldiers who casually murder unarmed civilians, smile sheepishly, and continue on their way; American "forces of liberation" who do the same to groups of so-called collaborators as they carry out a scorched-earth de-Natzification policy of the newly "liberated" territory; mild-mannered old country doctors in genteel rural hospitals who calmly dispatch their patients with lethal injections before making their way downstairs for supper. Every incident portrayed is based on well- documented events that took place in other occupied countries. Nobody is spared in Brownlow's profoundly pacifist analysis of the military mind-set. War and military occupation are presented as pits of horror and despair that are without bottom.

Ordinary, well-meaning people like Pauline Murray are swept along by forces far beyond their control into dark political whirlpools from which there is no escape. This is a chilling nightmare of a film that demands of every viewer that they ask themselves the question: What would I have done?

The ideas put forward in "It Happened Here" are so riveting even for a modern audience that it tends to be discussed mainly as a socio-political treatise and neglected as a film. And looked-at as a film, it undoubtedly has its faults. The acting, as one would expect from a group of amateurs, is uneven. Pauline Murray (who is very cleverly allowed to retain her own name in the film) was the wife of a doctor friend of the two Directors: she had never acted before. We see her technique develop as the story progresses (it was filmed more or less in sequence) and it is a process which, no doubt unintentionally, actually adds to the strength of the film. The story seems to emerge out of a naive daydream into something increasingly realistic and dreadful.

The film's mixture of documentary and narrative style, somewhat reminiscent of Citizen Kane, was an ambitious and thoroughly appropriate format, superbly well- realized with the help of such genuine news-reel voice-over artists as Alvar Liddell and John Snagge (who gave their services free). The staged "archive footage" of the Flanders Field Christmas Day football match would do credit to any professional production company, as would the use of rousing military music to establish and maintain atmosphere. Brownlow's skill in carrying us along with his appalling fantasy is rooted in his commitment to the project: we see German tanks everywhere when we know in our heart of hearts that Kevin was only able to get hold of one, because this is the world that we have agreed to enter into. There is no real interest in looking for the seams and the improvisations. We are involved in the realization of a nightmare. It is the spirit and the atmosphere of the piece that seize hold of us, not the limitations of the production budget.

I found this film disturbing, unsettling, unforgettable. The scale of the achievement involved in the creation of a work of this quality from such humble beginnings can hardly be overstated. I sincerely hope that you may get the opportunity to see it, because it is, I know, something of a rarity.