'Do you know what Strontium-90 is, and what it does?'

The story behind Peter Watkins's 1965 docu-drama The War Game is gnarled and contentious. Funded by £10,000 from a reluctant BBC at a time of power struggle inside the Corporation, the final 48-minute film made higher-ups profoundly uncomfortable. After privately screening The War Game for representatives of several government departments (including the Ministry of Defence, the Home Office and the Post Office), the BBC decided not to broadcast the film.*

The resulting imbroglio is detailed in Watkins's account, which makes fascinating reading for anyone interested in the raison d'état of the rump British Empire in the sixties. The BBC tried to shake off accusations of political censorship by screening the film to select elite audiences - specifically excluding film critics -, but scrupulously avoided showing it to a wider public. As Watkins stresses, the print media overwhelmingly backed the BBC's line (some choice quotes there).

The film's rehabilitation began when a limited theatrical run resulted in The War Game winning Best Documentary Feature during the 1966 Academy Awards. The BBC, which had previously claimed that it was only Watkins's artistic failings that had led them to suppress the film - as we all know, the Corporation cares deeply about our delicate artistic sensibilities, which is why Top Gear exists - finally broadcast The War Game in 1985, as part of the forty-year anniversary coverage of the bombing of Hiroshima. For his part, Watkins has continued as a stridently left-wing and anti-war documentary filmmaker, falling foul of censorship as often as he's won awards.

The War Game falls into three kinds of footage, mixed within the film. First, there are short interviews with a random sample of passers-by ('Do you know what Strontium-90 is, and what it does?') which reveal the British public as woefully underinformed on the horrors of nuclear war. Interspersed, there are monologues based on real recorded statements by authority figures in government, military and church, which tend towards the utterly insane presented with a certain cheer ('The Aztecs on their feast days would sacrifice 20,000 men to their gods in the belief that this would keep the universe on its proper course. We feel superior to them.')

The meat of the film and the source of most controversy, though, is a merciless recreation of the horrors of a Soviet nuclear strike on Kent, presented in the style of a documentary. A Chinese ground invasion of South Vietnam leads to the US authorising the use of tactical nuclear weapons - first in Indochina, then, as tensions escalate between the blocs, in Germany. This is followed by Soviet massive retaliation on targets in western Europe, including the UK. Apart from the millions killed instantaneously, much of British society collapses in the following months as radiation disease, starvation and post-traumatic stress overwhelm a totally inadequate civil defence system.

Filming around Tonsbridge, Gravesend, Chatham and Dover, Watkins uses almost entirely non-professional actors (ironically considering the director's left-wing stance, this caused him some trouble with actors' unions). He achieves a sense of extraordinary immediacy by using a lot of shaky handheld camerawork (old hat in 2012, revolutionary then), realistically imperfect dialogue, and seemingly unscripted moments. Among a talented crew, Lilian Munro's make-up work stands out for its unflinching recreation of injuries (severe burns, poisoning), skin covered in soot, and other misery.

All of which sounds a bit technical, so let me be clear, in the manner of the Prime Minister: The War Game is among the most horrifying films I've ever seen. I don't say that lightly or frivolously. In the many, many hours I've misspent watching exploitation films, only The Texas Chain Saw Massacre and Cannibal Holocaust have sickened me to my very soul to the same extent as The War Game. That's not because it's particularly explicit (much of the film works by suggestion), but because what is portrayed is just so much more gut-churningly awful than what even the most depraved horror directors tend to dream up: newly blind children covering their faces after the brightness of a thousand suns has burnt their retinas, people dying from carbon monoxide poisoning, others beaten to death by starving mobs.

In all that, Watkins is keen to stress that what he's portraying is not speculative but merely a dramatisation of existing scientific predictions. 'It's been estimated that...', begins sentence after sentence of horrifying statistics that imbue the film with a sense of inexorability. Reviewers were of course right to call The War Game totally one-sided: but who could imagine a 'balanced' film on this subject? A documentary that detailed the horrors of atomic fallout before enumerating the many wonderful upsides of nuclear weapons would surely be more repulsive than The War Game, not less.

There is, then, a disgusting hypocrisy in the official response to The War Game. According to the defence and media establishment, planning the murder of millions upon millions of civilians is quite all right just so long as one uses the correct euphemisms; the moral transgression apparently lies in spelling out the reality. As Orwell said, the genocidal reality of modern power 'can indeed be defended, but only by arguments which are too brutal for most people to face, and which do not square with the professed aims of the political parties'. Hence the need for obfuscating language and misinformation - which, as Watkins points out, is precisely likely to increase casualties in the eventuality of war.

A mere calm listing of the inevitable horrors of all-out atomic war would refute any case for nuclear weapons, but that's not all Watkins does. By focusing on the darker aspects of Allied conduct in the Second World War, he critiques the justifying ideologies of British power. Again and again, the narrator stresses that the scenario is merely an extrapolation of what happened to Hamburg, Darmstadt, Dresden, Hiroshima and Nagasaki: and who dropped those bombs? When the firestorm created by a one-megaton bomb destroys Rochester, 'the oxygen is being consumed in every cellar and every ground floor room'. Which is how 42,000 civilians died during Operation Gomorrah, after Bomber Command developed the proper scientific combination of incendiary and explosive bombs to create a firestorm. After the initial Soviet attack, Watkins describes British bombers on their way to retaliation. 'Their target: people like this.'

It's really no surprise, then, that The War Game was thought excessively subversive, and its suppression on explicitly political grounds defended in the press. '[T]he only possible effect of showing it to the British public at large would be ... to raise more unilateral disarmament recruits', the Evening News insisted.** The entirely correct accusation against Watkins was thus one succinctly expressed in the hideous German word Wehrkraftzersetzung, literally 'sapping of defensive strength': the danger of showing the film would be to incline the British people against any possibility of a war they'd been systematically misinformed about.

All of which might be interesting historically, but unfortunately the BBC is still at it. Acting as the mouthpiece of the government in the run-up to the conquest of Iraq, refusing to broadcast humanitarian appeals when the aggressor happens to be a is a British ally, shutting down commentators who wouldn't fall in line during the riots: more than ever, the BBC has a reputation for being regime media - structurally, not just incidentally. All the more reason to hold up The War Game as the little docu-drama all the Corporation's horses and all the Corporation's men couldn't bury.

*The BBC officially denies this screening ever happened.
**According to Watkins's website.