The opening credits of ‘The Ash Tree’ describe it as “A Television Version by David Rudkin” – not an adaptation of M.R. James’s 1904 story, but Rudkin’s version. The BBC had always allowed their writers plenty of freedom in interpreting James. In The Ash Tree, that means stripping away the conversational first-person narrative in favour of wide-open spaces and ominous silences.

On the surface, this makes it quite similar to Jonathan Miller’s original Christmas ghost story, ‘Whistle and I’ll Come to You‘. Underneath the surface, though, something else is at play. A year prior, Rudkin had written Penda’s Fen (1974), directed by Alan Clarke as part of the BBC’s Play for Today strand. Rudkin never saw Penda’s Fen as a horror story, describing it as “a bloody political piece”. Nevertheless, it has been retrospectively canonised as part of the folk horror wave of the late 1960s and early 1970s.

Its cult has grown enough to support a book of essays, Of Mud & Flame: The Penda’s Fen Sourcebook, published in 2019 and taking its title from its hero Stephen’s closing credo:

“I am nothing pure. My race is mixed. My sex is mixed. I am woman and man, light with darkness, mixed, mixed! I am nothing special, nothing pure. I am mud and flame.”

If you had to name a cultural institution that was the exact opposite of that, you might suggest the British aristocracy. Aristocracy stakes its validity on the pure, unmixed bloodlines that Rudkin spends the whole of Penda’s Fen arguing cannot really exist. He might be working in a more conventional horror format than Penda’s Fen – which itself has plenty of shocking and frightening scenes – but the country house setting and nobleman protagonist of ‘The Ash Tree’ means that yes, this is another of Rudkin’s ‘bloody political pieces’.

‘The Ash Tree’ begins with Edward Petherbridge’s Sir Richard riding over to Castringham Hall, the Suffolk house he has just inherited. The locals seem unimpressed; one notes that he’s “not pale enough to be a Lord,” while a child mistakes him for the previous squire, Sir Matthew. Already, then, the aristocracy is linked with racial homogeneity and a lack of meaningful change. The child’s confusion is also our first hint at the play’s narrative drive, one which Rudkin has found by rearranging the events of his source.

James’s story is strictly chronological, beginning with the career of Sir Matthew, whose account of witchcraft sent a local woman to the gallows. In Rudkin’s script, this happens just after the half-way mark, roughly the point at which James introduces Sir Richard. With Richard repositioned as our viewpoint character, Rudkin introduces us to Matthew in a series of strange visions of the past.

The fact that Petherbridge plays both Richard and Matthew makes the status of these sequences ambiguous: is it a true flashback to the past, or a hallucination where Richard imagines himself as his ancestor? Whatever it is, it is clear that by inheriting the Hall, Richard has taken his ancestor’s sins on as his own.

Another key to understanding ‘The Ash Tree’ comes from the landscapes, beautifully captured by camera operator John McGlashan, who had previously shot ‘A Warning to the Curious‘ and ‘The Stalls of Barchester‘. They are visually empty but aurally full, with Petherbridge’s cut-glass English sounding quite out of place among the distant sheep, calling birds and lowing cows. It’s no surprise that another animal sound – a strangely treated recording of insects chirping – heralds each vision.

Part of the cultural stew that brought forth folk horror was the hippie-era rediscovery of older theories about earth energy and ley lines. Glastonbury Festival, which actually takes place in Pilton, was named in homage to the neopagan, Arthurian, Biblical and astrological ideas which had made the nearby village a place of pilgrimage for the nascent New Age.

Among the ideas being unearthed by the hippie generation was the Roman concept of the genius loci, a guardian spirit specific to a particular place. By the late 20th century, this concept had been expanded by writers like Alexander Pope, who took the idea of a “spirit of a place” metaphorically, to mean the feel or character of a particular location. Penda’s Fen was driven by Rudkin’s desire to “write something that grew out of the landscape”, and a similar sense of genius loci – in both the colloquial and supernatural senses – is at play in ‘The Ash Tree’.

Time is almost irrelevant in the film’s structure. One scene ends with Richard halfway through a sentence, then the film cuts to him finishing it in a completely different location as though no time has passed at all. If you want to understand the chain of cause and effect that leads to the film’s terrible conclusion, merely knowing what happened when is no help. What matters is a place, its character and the accumulation of horrors it has seen over the years.

This theme is developed from James’s story, which has a sense of tragedy returning in cycles, but the mystical tone of the finished film, the suggestions of time-slips and visionary experience, are native to Rudkin’s work. His other main theme, the idea of Britain as a lawless, pagan “mongrel nation” which authoritarians are fated never to contain, is also present and links ‘The Ash Tree’ to the wider folk horror movement.

What, after all, is The Wicker Man (Robin Hardy, 1973) about, other than a modern Christian authority figure realising that his country harbours older, darker traditions? It’s no wonder people kept mistaking Rudkin’s political writing for horror when the defining British horror subgenre of the time was so rich in thoughts about national identity, progress, faith and history. There is even a Jamesian return-of-the-repressed cycle to folk horror’s popularity. It first flourished in the early ’70s, a time of economic stagnation, generational division, terrorism and uncertainty about Britain’s future. Its return to popularity has taken place in an era with all of those problems, but without David Bowie.

The difference between Rudkin’s writing and other folk horror is a question of sympathy. Lord Summerisle is an unusually likeable and genteel character for Christopher Lee, but The Wicker Man still works for audiences who see him as a straightforward villain. By contrast, Rudkin always prefers the old ways to the new, seeing in them a tolerance and a lack of hypocrisy that modern Britain could learn from.

In Penda’s Fen, the sickness of post-pagan society was represented by censoriousness and homophobia. In ‘The Ash Tree’, it’s misogyny, displayed in the violent campaigns against witches. The effect is much the same, painting authority less as a natural hierarchy and more as a psychosexual disorder. As the accused witch Anne Mothersole, Barbara Ewing is stripped and interrogated in scenes that clearly point up the male neuroses underpinning the witch panics. The drama ends by handing control of the story back to its women, showing Lalla Ward – three years before she played Romana in Doctor Who – uncovering its final horror.

But what is it? No doubt that the final sequence of ‘The Ash Tree’ is one of the most graphic, grotesque, disturbing sights in any of the Christmas ghost stories, but there will be no spoilers here – it should be experienced, not described. ‘The Ash Tree’ constantly champions first-hand sensory experience over tradition, repeating the line “What I have seen, I have seen.” How apt that it ends with a moment designed to get the viewing public sat bolt upright, wondering what, exactly, they just saw.