The 700-year-old Clermont-Tonnerre Grail: an illuminated manuscript telling tales of King Arthur and his court

The book has the heft and dimensions of a church Bible. The front and back boards, made of wood, are upholstered in velvet that is a deep and variegated green, like ancient moss. There are four weighty brass cornerpieces, each decoratively scrolled like a Victorian balustrade. On the front cover are two fastenings made of the same yellow metal: the contents of the book are precious, and it could once be closed tight like a traveller’s trunk. Gilt letters embossed on the spine reveal the theme: Roman de Artus.

This is the 700-year-old Clermont-Tonnerre Grail, which tells in Old French the ancient stories of King Arthur and his court. It is to be auctioned in the Valuable Books and Manuscripts including Cartography sale on 8 July 2026 at Christie’s in London. The volume contains three separate but connected narratives, all beautifully illustrated with historiated initials: miniatures that depict episodes from the tale.

The first text, known as Joseph d’Arimathie or L’Estoire del Saint Graal, provides a history of the Holy Grail, how it was brought to Britain and became the object of a chivalric quest. The second part, L’Estoire de Merlin, is a kind of life story of the wizardly éminence grise behind the throne of Uther Pendragon, father of King Arthur. The third section, known as the Suite Vulgate, follows on from the Merlin biography, and gives an account of the turbulent early years of Arthur’s reign.

These three romances are the opening section of a much larger cycle of Arthurian literature that covers Lancelot’s adulterous love for Guinevere, Merlin’s downfall and Arthur’s death. Such legends, recorded in various overlapping iterations, were enormously popular in early medieval France — they were the bestsellers of their day — and continued to be admired into the 17th century (which is when that weighty binding was made for the manuscript’s owner, Charles-Henri de Clermont-Tonnerre).

But who wrote the version of the story in this book? We know that the Joseph and Merlin are prose adaptations of epic poems conceived early in the 13th century by Robert de Boron, a writer of romances from eastern France. In a kind of foreword to Joseph d’Arimathie, Robert says that he has merely translated from Latin a work that Christ himself dictated to an unnamed hermit. He is claiming, in other words, that his story is historical fact, and that it bears the stamp of divine authority.

The third text is by an anonymous author who may have worked to Robert de Boron’s scheme, or taken it upon himself to finish the story. All three narratives bear the marks of the Lorraine dialect: the Clermont-Tonnerre Grail speaks with an accent that is very likely Robert’s own. And there is one crucial and enduring element of the story — the Holy Grail — that seems to be entirely the product of Robert de Boron’s own imagination.

In the ‘Perceval’ romances that came before Robert de Boron, it was unclear exactly what kind of object the grail was (it was sometimes referred to as a ‘jewel’). Chrétien de Troyes, who wrote a grail story a few decades earlier, implies that the grail is a flat platter, suitable for serving fish. It is a somewhat mysterious artefact, but it is not inherently sacred. To him, it is a merely a stage prop, an incidental piece of silverware.

Robert de Boron’s great narrative leap was to provide the grail with a sanctified back story. He is the first writer to say that it is the cup used by Christ at the Last Supper. More than that, he claims that Joseph of Arimathea, who in the Bible account organised Jesus’s burial, received the grail from the hand of Pontius Pilate, and used it to collect some drops of blood from Christ’s crucified body.

Robert’s imagination transformed an undistinguished dish into an object of power. His vision of the grail quickly became embedded in Arthurian myth, and remains an unquestioned element of the story these many centuries later. Fictions from Indiana Jones and the Last Crusade to The Da Vinci Code, and writers from T.H. White to the Monty Pythons — they all owe a debt to Robert de Boron’s novelistic mind.

So the grail is decidedly a cup or a chalice in the Clermont-Tonnerre book — but that message seems not to have got through to the artists who illustrated it. Wherever the grail is depicted in the initials, it appears to be something like a monstrance, the frame used to display the host in the Roman Catholic mass. But it is hard to tell, because the relic is always shown draped in a veil. Perhaps this was the artists’ way of emphasising the grail’s enigmatic nature, while judiciously glossing over the fact that they did not know what it was supposed to look like.

There are 126 historiated initials in the 241 leaves of the Clermont-Tonnerre Grail, and they are a wonderful addition to the book. They were painted in Metz, where the manuscript was written, and seem to be the work of a group associated with an artist known as the Master of the Liège Apocalypse.

Every initial is a vibrant and subtly witty tableau, a snapshot in miniature of a scene described in the text. In the first book, we see Joseph of Arimathea lying in bed, looking up at a hovering angel who is commanding him to father a son. His wife lies beside him in her nightcap, fast asleep and oblivious to the otherworldly presence in her bedchamber. Further on, there is a picture of Nascien, a forebear of Galahad, who finds himself stranded on a magical island that turns on its axis like a carousel. He, too, can only doze, his head resting wearily in his palm, as the motion of the island churns the green sea around him.

There are many initials that depict the enchanter Merlin, and the illustrators have eagerly embraced his miraculous ability to take on the appearance of other living things. One initial — a closed ‘C’ — shows Merlin in the form of a stag, bounding past the dinner table of a princess named Avenable (meaning ‘lovely’). She and her entourage look on as the rampant animal knocks a goblet of wine to the floor.

In another miniature, Merlin is shown as a humble shepherd. He calls up to a pair of indifferent sentries on the ramparts of Camelot, and his sheep are ranged at his feet in an unfeasibly straight line. Twenty pages later, Merlin has turned himself into a black knight on a black charger, leading Arthur’s cavalry into battle. He holds aloft a banner that he has transformed into a fire-breathing dragon, which spews a stream of red fire across the empty upper margin of the page.

The Merlin described in the Clermont-Tonnerre Grail is the very archetype of a wizard: grey-bearded and unbiddable, strategic and far-sighted. Practically all the wizards of world literature, from Shakespeare’s Prospero to Gandalf and Dumbledore, bear a family resemblance to the medieval magus of Camelot. Yet Robert de Boron’s Merlin is a more complex and perplexing spell-weaver than his distant descendants. In one passing episode, he laughs at a peasant who has spent money on leather to mend his shoes, because his supernatural foresight tells him that the man will not live long enough to wear them.

That many-faceted, somewhat sinister characterisation is perhaps Robert de Boron’s other great contribution to grail legend. In this telling, Merlin’s dark side is rooted in the fact that he was fathered by a devil who deceived his unwitting mother. The wizard’s much-used gift for metamorphosis comes from the same demonic source, and it is only his mother’s virtuous nature that makes it possible for Merlin to use it for good — though not entirely, and not always. In an echo of his own conception, Merlin deploys his shape-shifting magic to make Uther Pendragon appear to be the Duke of Tintagel, so that Uther can seduce the duke’s wife, Ygraine. Merlin colludes in this because he knows that a son will be born of the encounter, and that the boy will become Arthur, the destined king.

Good and evil are thus inextricably bound together — and not just on the vellum pages of this book, but in Merlin’s soul and in every human heart. Therein perhaps lies the appeal of Arthurian lore, the reason the stories told in the Clermont-Tonnerre Grail are still known and recounted today. Their forms may change, like Merlin or the grail itself. But like all genuine myths, they are truer than if they had actually happened.

Valuable Books and Manuscripts including Cartography is on view 3-7 July 2026 at Christie’s in London

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