Tintagel from Arthur's Castle.

‘The island of Tyntagel’ – which was connected to the mainland by a narrow land bridge.

In May 1233 the younger brother of Henry III, Richard, Earl of Cornwall (1209–72), exchanged three of his manors for a small parcel of land on the north Cornish coast.

Richard proceeded to build a castle here, with an outer bailey on the cliff tops of the mainland and an inner ward with a great hall and chambers on the headland. But as castles went, this was a fairly small and unimpressive creation, and its location made it next to useless. What attracted the earl to Tintagel was something else, something literary: a reference in a text written in the previous century, the History of the Kings of Britain, by the cleric Geoffrey of Monmouth. Arthur mania is born.

Recollect: Uther Pendragon, is driven mad with lust for Ygerna, the wife of one of his barons, Gorlois of Cornwall. Gorlois prudently removes his wife to an impregnable stronghold on the coast, the castle of Tintagel, but then rather less prudently withdraws to another fortress nearby. The pursuing Uther and his men inspect Ygerna’s refuge and realise that no ordinary attack can succeed:

The castle is built high above the sea, which surrounds it on all sides, and there is no way in except that offered by a narrow isthmus of rock. Three armed soldiers could hold it against you, even if you stood there with the whole kingdom of Britain at your side.

At this point in the story, Merlin proposes a supernatural remedy: by means of a magic potion, he transforms Uther into the exact likeness of Ygerna’s absent husband. The ruse is entirely successful. The guards of Tintagel allow him into the castle, and Ygerna takes him into her bed.

That night she conceived Arthur, the most famous of men, who subsequently won great renown by his outstanding bravery.