“We’re knights of the Round Table/We dance when ere we’re able/We do routines and chorus scenes/With footwork impeccable”. Over the course of a minute-long song, the Monty Python team managed to turn Camelot, for so long held up as a shining beacon of democracy and hope, into, in the words of Graham Chapman’s despairing King Arthur, “a silly place”. And yet the irony is that, in their deliberately bathetic presentation of the Arthurian myth in 1975’s Monty Python and the Holy Grail, the directors Terry Gilliam and Terry Jones presented a far more realistic presentation of the story than the vast majority of other filmmakers have managed to, the Knights Who Say “Ni!” and the Holy Hand Grenade of Antioch notwithstanding.

To the considerable number of directors who have attempted their very own crack at the Knights of the Round Table can now be added Zach Snyder, maker of Watchmen, 300 and, somewhat notoriously, Justice League. Snyder has been vague about the project, saying in an interview that, “I’m working on something but we’ll see. I’ve been thinking about some kind of retelling, like, [a] real sort of faithful retelling of that Arthurian mythological concept. We’ll see. Maybe that will come at some point.”

The director has often cited the King Arthur story as a major influence on his work, even down to large parts of his film Batman vs Superman being explicitly inspired by Thomas Malory’s Morte d’Arthur. He even included the visual allusion of a poster for John Boorman’s 1981 Malory film adaptation Excalibur (his favourite film) in an integral scene, just in case the audience didn’t entirely get his reference.

Save Excalibur, it is hard to think of any credible cinematic portrayal of the Arthurian myth

Snyder’s films have attracted a mixed reaction to date. Although 300, a camp and overblown retelling of the Battle of Thermopylae, was an enormous box office success, he attracted opprobrium for his over-simplified adaptation of Alan Moore and Dave Gibbons’ Watchmen, followed by increasing anger at the liberties that he took with various superhero narratives in Man of Steel, Batman vs Superman and Justice League. He has been pilloried for prizing a flashy visual style over storytelling coherence, and a fast and loose attitude towards the stories that he has adapted that means that his intention to come up with “a real sort of faithful retelling of that Arthurian mythological concept” should be taken with a substantial pinch of (Himalayan pink) salt.

Yet whatever Snyder comes up with, it cannot be any worse than the last few cinematic attempts to adapt the story of King Arthur. Like natural disasters, they seem to arrive about once a decade and leave chaos and devastation in their wake. The most recent offender was Guy Ritchie’s appalling King Arthur: Legend of the Sword, which gaily jettisoned most of the traditions of the narrative – no Grail Quest, no Guinevere, no Lancelot – in favour of war elephants borrowed from The Lord of the Rings, an embarrassed-looking Jude Law transforming himself into a demonic computer-generated knight and characters named things like Back Lack and Kung Fu George. Had it been played for laughs, it might have just about worked, but what can you really say about a film where a cameo by David Beckham is neither the most embarrassing nor incongruous thing about it?

Ritchie’s ignominious piece of bastardry has followed other, equally dismal flops. In 2004, Clive Owen essayed the role of Arthur in Antoine Fuqua’s eponymous film, with Ioan Gruffudd as Lancelot, Keira Knightley as Guinevere and Stephen Dillane as Merlin. The critic who cruelly but accurately noted that Owen’s king had all of the charisma and leadership of a geography teacher supervising a gaggle of surly schoolboys on an outward-bound weekend away should have been given at least an OBE for services both to honesty and to film criticism.

The film’s small-scale, rather haphazard scope means that it seldom turns into the grand adventure that the publicity promised, even if it was intended to be a more historically accurate account of the legend that transposed its setting into the fifth century AD and attempted to deal with the consequences of the decline of the Roman Empire in Britain. It may conceivably have been an interesting attempt at deconstructing the Arthurian legend, but its producer Jerry Bruckheimer and a director best known for the gritty cop thriller Training Day were distracted by the demands of a blockbuster budget, and so it, too, joined the ranks of the second-rate. Still, there’s a cracking ice battle (no pun intended) halfway through to ameliorate boredom.

Hollywood seems unable to produce an accurate and definitive account of the legend

But save Boorman’s Excalibur, which we shall come to, it is hard to think of any credible cinematic portrayal of the Arthurian myth. Jerry Zucker’s First Knight was doomed by its badly punning title, and its lukewarm depiction of a love triangle between Sean Connery’s grizzled Arthur, Richard Gere’s luxuriantly bewigged Lancelot and Julia Ormond’s Guinevere was overshadowed by the kitsch set design of Camelot, which owed more than a passing resemblance to Disneyland. The apparently endless 1967 film adaptation of the Broadway musical Camelot was much criticised for its funereal pace and identikit songs, to say nothing of the lugubrious presence of Richard Harris in the lead. And such Fifties swashbucklers as Knights of the Round Table and The Black Knight, while enjoyable enough hokum, are less faithful representations of the story and more quota costume dramas that bear the most tendentious resemblance to both historical and narrative accuracy.

Hollywood seems unable to produce an accurate and definitive account of the legend, but the difficulties may lie in the source material. The most famous extant literary version of the story, Thomas Malory’s fifteenth-century Le Morte d’Arthur, is a long and complex treatise on courtly love, honour and knightly integrity, which was composed while Malory was in prison, accused of rape, attempted murder and robbery. (Perhaps he, too, will be retrospectively cancelled if Snyder’s film is ever made.) While it remains the definitive account of the myth, Malory’s tale is more often studied than read for pleasure. It is instead T.H. White’s adaptation, The Once and Future King, that is best known today, not least for the Disney animated version of the first book in the series, The Sword in the Stone. Yet White’s account sanitises and softens much of the integral darkness and strangeness of Malory’s original, introducing stronger comic elements and anachronisms that some have considered jar with the gradually grimmer tone that exists throughout the narrative.

The Arthurian tale as depicted by Malory is a complex one

Unlike the Robin Hood saga, which has its straightforward heroes and villains, the Arthurian tale as depicted by Malory is a complex one. Arthur is no straightforward hero but a man wracked by complex urges, at one point drowning every newborn boy in his country in an (unsuccessful) attempt to kill his illegitimate (and incestuously born) son Mordred. The most dynamic and virtuous character, Sir Lancelot, is engaged in an adulterous affair with the king’s wife Guinevere. And it all builds to an apocalyptic climax in which the forces of evil are nearly triumphant. It is a dark, morally compromised world, in which knightly virtues are found wanting at all times. Little wonder that Hollywood has found it difficult to adapt it into a feelgood account of heroism and swordplay, despite the considerable liberties that have been taken with the narrative.

Which is why Excalibur, for all of its eccentricities and silliness, remains, along with Robert Bresson’s Lancelot du Lac and, inevitably, Monty Python and the Holy Grail, the most convincing film version of the Arthurian legend. The story is told in a strange, almost phantasmagorical fashion, with music by Wagner and Carl Orff, and juxtaposes grim medieval realism with operatic flourishes. It is most notable today for featuring many actors who went on to be household names (including Patrick Stewart, Liam Neeson and, as the dastardly sorceress Morgana le Fay, Helen Mirren) and for the mercurial Nicol Williamson’s quixotic performance as the sorcerer Merlin. Boorman was aware that Mirren and Williamson had previously had an ill-fated love affair, and believed that their casting as antagonists would feed on their real-life antipathy towards one another, and he was correct. Their scenes together are electrifyingly barbed, with more than a touch of Who’s Afraid of Virginia Woolf, albeit with more broadswords and spells.

If the film’s lead actors Nigel Terry (as Arthur) and Nicholas Clay (as Lancelot) never make much of an impression, then this is perhaps an intentional nod on Boorman’s part to how heroic idealism usually comes off second best to grim reality. And in the film’s unabashed nudity, sex and violence, it presents an adult-oriented version of Arthurian myth that is a million miles away from the more sanitised swordplay that Hollywood has served up before and since.

It remains to be seen what Snyder’s film comes up with, and whether it manages to say something engaging and original about the ideas of honour and duty that other accounts of the tale have largely struggled with. But even if it is never made, or is disappointing, perhaps the pithiest comment on the Arthurian ideals comes in Monty Python and the Holy Grail, in which a passer-by asks a corpse collector who the leader of the bedraggled knights, miming their way on imaginary horses, is, and is told, “Dunno. Must be a king.” When asked why, the corpse carrier replies, deadpan, “He hasn’t got shit all over him.”