The problem with historical dramas is they are stuck in the past. Which is why Jez Butterworth hasn’t made a historical drama. Of course, Britannia (which starts on Sky Atlantic, 18 January) is loosely based on the events surrounding the second Roman invasion of Britain in 43 AD. But regarding it as a literal attempt to tell that story would be akin to regarding The Wicker Man as the story of a missing child.

Robin Hardy’s cult masterpiece was a story of neurotic orthodoxy colliding with something stranger and wilder. And Britannia similarly upsets conventional assumptions, taking British restraint and moderation into a dusky glade, ramming hallucinogenic mushrooms down its gullet and waiting for its darkest, most fanciful imaginings to spew out.

It’s not simply understandable that Britannia plays fast and loose with literal history. It is correct and even important that it does. This is a show about the power of myth-making. In place of historical precision, there is something much more potent and seductive – a berserk and atavistic idea of Britain, odd notions and practises developing in isolation.

Into this maelstrom come the forces of Emperor Tiberius, with their discipline, their road-tested, state-of-the-art invasion strategies and their assumptions of cultural superiority. They are entirely unprepared for Albion’s array of stinking, babbling visionaries, terrifying mystics and warrior queens who threaten them by saying: “If you ever come here again, I will eat your eyes.” No wonder the legions are uneasy.

Reece Shearsmith … getting his hands dirty in A Field in England. Photograph: Alamy Stock Photo

It has been suggested that Britannia will fill a Game of Thrones-shaped hole in Sky Atlantic’s schedules this year. But actually, it’s precedents are far less obvious. In fact, Britannia is a worthy addition to the ever-growing canon of British neo-folk art.

In what feels like a fitting coincidence, a new audio version of Piers Haggard’s 1971 witchy chiller, The Blood on Satan’s Claw, arrives later this week. Mark Gatiss, Reece Shearsmith and Alice Lowe will reimagine the tale for Audible. Shearsmith was also in Ben Wheatley’s 2013 psychedelic Civil War drama A Field in England, another folk horror descendant. There was also 2017’s The Levelling, which mined muddy, brutal revelation out of the age-old clash between rural and urban England.

In music, there’s Richard Dawson, residing at the point where the folk storytelling tradition meets the avant garde, Lisa Knapp’s radiant refittings of traditional musical texts and even James Holden making implicit connections between rave and dizzying pagan rite. Like Britannia, these works tap into the ancient and the modern, exploring the resonances of the past through the filter of the present.

We also have Detectorists. Mackenzie Crook’s cracker even shares a visual grammar with Britannia: artfully sunlit close-ups of crows and flowers; nature at its oddest and most vivid. The Detectorists are wistfully looking underground for traces of Britannia: something strange and untamed beneath middle England’s municipal fields. What is literally and figuratively submerged in the sensibility of Detectorists is bloodily overt in Britannia. And fittingly, Crook, now a long, long way from Gareth Keenan, also appears in Britannia, as terrifying Druid head-honcho Veran. Last year, in a New Statesman interview, Crook was asked if he believed in ghosts. “I love the idea of them”, he replied. “Voices from the past, calling to us.” This notion is palpably at the heart of both Detectorists and Britannia.

This is a particularly sensitive moment to be exploring British identity. Brexit is, of course, the rampaging elephant in the room. Brexit represents the desire to interpret these currents in the most literal way imaginable. With a central premise involving a superpower from mainland Europe trying to subdue the plucky Brits, only to discover it’s bitten off more than it can chew, it is just about possible to imagine a pro-Brexit narrative being constructed around Britannia.

But really, it is the opposite. There is a new, outward-looking folk tradition being established, characterised by curiosity about submerged history but also, crucially, by a refusal to lapse into nostalgia by simply regurgitating that history. That way lies a shrinking aesthetic gene pool. This way lies a creativity that is simultaneously deeply rooted in the past and constantly evolving into uncanny new shapes – as has been the open-minded, globally influenced case with most of the best of Britain’s creative output. At a time of cul-de-sac nativism, Britannia is part of a tradition that currently feels more valuable than ever.