The Holderness Coast is what geologists call a soft coast. The cliffs and low ground are formed of glacial till - boulder clay laid down by the retreating ice sheets ten thousand years ago. Boulder clay is soft. Boulder clay slumps in rain. Boulder clay collapses into the sea when the waves undercut it. The Holderness coast is retreating at roughly two metres a year, faster in places, and has been doing so since the ice retreated. Every village built within striking distance of the cliff edge in the Middle Ages has either been moved inland, swallowed entirely, or both. The North Sea is patient. It takes a metre here, a field there, an entire street in a single winter storm. Over centuries the loss is measured in kilometres. Ravenspurn was on the seaward end of the peninsula that still curls into the Humber's mouth. Its sister-town of Ravenser Odd had already been flooded in the fourteenth century. Ravenspurn followed.

In July 1399, Henry Bolingbroke - banished by his cousin King Richard II - landed at Ravenspurn with a small force of supporters. He claimed at first to be coming only to recover his confiscated Lancastrian inheritance. By August he had Richard in custody. By September he was Henry IV, King of England. Ravenspurn was the first English ground Henry touched. A cross was later erected to mark the landing place, but as the coast retreated the cross was moved - first to one location, then another - and eventually to Holyrood House in Hedon, where it survives today. The town from which it was rescued does not. Shakespeare understood the symbolic weight of the place. In Henry IV Part 1, the Earl of Northumberland reminds his son Hotspur of the day they 'met him then, both well at Ravenspurgh.' The audience in 1597 would have recognised the name. The town might already have been disappearing into the sea even as the play was first staged.

Seventy-two years later, in March 1471, Edward IV repeated the landing. Driven into exile in the Netherlands the previous year by the Earl of Warwick - the 'Kingmaker' - Edward returned with an army to reclaim the throne. He came ashore at Ravenspurn for the same reason Henry had: it was the closest workable landing point on the Yorkshire coast for a force coming from the Low Countries, sheltered to some extent by the spit at the Humber's mouth. The local lord, Sir Martin de la See, attempted to resist Edward's landing. He failed. Edward marched south, gathered support, fought and won the battle of Barnet on 14 April, fought and won the battle of Tewkesbury on 4 May, killed the Lancastrian Prince of Wales in the rout, and within weeks had Henry VI dead in the Tower of London. The Wars of the Roses essentially ended at Tewkesbury. They began, for Edward, on a beach at Ravenspurn.

The peninsula Henry and Edward stepped onto still exists - it is the Spurn Head spit, the curling tongue of sand that defines the mouth of the Humber. But the town is gone. The exact site lies somewhere beneath the modern North Sea east of the spit, in shallow water that has been drilled in recent decades for the Ravenspurn gas fields. From the air, the Holderness Coast still shows its slow surrender. Cliffs of brown till retreat year by year. Caravan parks built too close to the edge have lost rows of vans to single winter storms. The villages further inland - Easington, Kilnsea - watch the sea coming. Some homes have already been demolished by the local council to forestall collapse. Sea defences have been built and rebuilt and given up on. The same boulder clay that crumbled away under Ravenspurn is still crumbling. The same North Sea that buried two king-making harbours is still rising. Henry IV's landing cross sits safe in Hedon. The town it commemorated is fish habitat now.