Alan Clarke’s visionary coming-of-age dream still lingers in the minds of 1970s children.

‘You can tell he’s not a nice man because of his television plays.’

So says Stephen Franklin (Spencer Banks), possibly the screen’s least hip tortured teenager, referring to a fellow inhabitant of the village of Pinvin, the lefty playwright Arne (Ian Hogg). Stephen is wholly on the side of the Mary Whitehouse-alike figure popping up in the papers in wanting all this 70s permissiveness and insurrection off the air. He prefers Elgar to rock n’ roll, believes in supporting ‘the Aryan national family on its Christian path’ and is, generally, a priggish, self-righteous, eminently slappable sort. But all this is about to change in writer David Rudkin’s utterly unique 1974 Play for Today. The line seems wryly prescient about Alan Clarke, who hadn’t become pegged as the controversial chronicler of Britain’s violent criminal underclass yet – that reputation began in earnest three years later with Scum. Penda’s Fen would appear to be an odd item on his CV:* it’s rural rather than urban, mystical and elliptical rather than plain speaking, and is largely concerned with the kind of Worcestershire villagers that Radio 4 makes dramas about, rather than the working class ne’er-do-wells that would come to dominate his later social realist works. And this most definitely goes beyond the bounds of social realism.

For Stephen, military cadet, church organist and son of a parson, starts to have dreams and visions, and dreams that turn to visions, interfering with his certainties and upsetting the status quo. He has dreams of sweaty heaving rugby scrums that it wouldn’t take an advanced Freudian to interpret (underlining the repressed enthusiasm he has for the saucy milkman). He will see an angel on the riverbank and a demon in his bed, cracks growing in the church floor, and an unsettling image of smiling mutilation in the Elysian grounds of a country mansion. He will see an aged Elgar himself during a rainstorm and chat with him about the secret of the Enigma Variations. Even his village’s identity becomes slippery. Is it Pinvin, Pinfin, Pendefen? Could it be Penda’s Fen, burial place of the last pagan king of England? Already an outcast at school for his grating piety he will be subjected to increasing humiliations that the masters ignore or condone. He is not what he thought he was. Certainties of race, sexuality and religion are stripped from him, leading to his climactic acceptance of his new identity during a strange confrontation in the Malvern Hills.

Penda’s Fen is an odd beast, a coming-of-age drama of sorts laced with elements of folk horror, full of psycho-geographical ruminations about the layers of history and endless meanings contained within the English landscape. The camera seeks out the sacred and arcane, the choir sings William Blake. It wouldn’t be a 1970s TV drama without earnest political arguments in the Parish hall. But here conversation also turns to the heresy of Manichaeism and the fact that the word ‘pagan’ originally meant ‘belonging to the village’. Modern music and media are unseen and unheard. Clarke’s treatment of the weirder elements is deft and physical and unfussy, his demon is a dark gargoyle straddling Stephen as he wakes from his wet dream slumber, like Fuseli’s nightmare, winningly sticking around when the light’s turned on. He drops out the sound for the hazy visionary sequence where children queue to get their hands lopped off save for the noise of the chopper hitting home. The appearance of Graham Leaman as Elgar sticks in the memory, in his dotage and wheelchair-bound, a ghost haunted by memory. But Clarke was always good with actors, and there are a fair few striking performances here.

It’s not perfect, a sub-Quatermass strand about a horribly burned youth and secret military bases underground is unceremoniously shelved after a substantial build-up. The pacing is uneven, dragging in the early stages, going bonkers in the latter, with a penchant for dense theological discussions in the cornfields in a decidedly ‘tell, don’t show’ mode. It’s a tying together of disparate elements into an ungraspable whole, and I doubt even its biggest fans would claim to wholly get what Rudkin’s getting at in places, but the mysterious is part of its DNA and part of its charm. It carries a rare emotional heft, aims for the visionary and actually gets there. Stephen’s ‘I am nothing pure!’ speech at its climax is unexpectedly rousing, a rallying cry for an alternative England. You can see why it lit a spark in the likes of the young Grant Morrison.

The fact that there were only three channels meant that the one-off TV plays of the 70s could draw a sizable audience no matter how abstract or intractable they were. Beamed once or twice into millions of homes and then never seen again they would often linger as a series of singular images and ideas long after the title and tale had been forgotten. Penda’s Fen is a perfect example of this, a film with followers who might not know its name but remember gargoyles in bedrooms and burning men on green hillsides. It’s wonderful that it’s finally getting a decent release 40-odd years after it first came into the world, its themes still resonant, a strange and impure child.

Mark Stafford

* Then again, this is the man who gave you Billy the Kid and the Green Baize Vampire, cinema’s only snooker-based horror musical. Which is an odd item on anybody’s CV.