Every Robin Hood story needs its villain, and for centuries that villain has worn one title above all others: the Sheriff of Nottingham. Cruel, greedy, complicit in every injustice done to the poor of Sherwood while good King Richard bled for Christendom on crusade and wicked Prince John schemed at home. It's one of the most durable double acts in English folklore.

But strip away the ballads and pantomime, and the officeholders behind that legendary title were real men, doing a real and often thankless job. One of the strongest candidates for the historical figure behind the "bad" sheriff of the Robin Hood tales is a man called William de Wenneval (his name also appears as Wendenal, Wendeval, or Wendenall, depending on which chronicle or charter you're reading: spelling in the 1190s was a moving target). He is a minor figure in the great chronicles, mentioned only in passing by Roger of Howden.

But the little that survives of his story is enough to suggest he paid an appalling price for his loyalty.

York Castle in 1190 was a large motte-and-bailey complex, not merely a tower. The Jewish community was trapped in the inner stronghold on the motte. Although this is usually reconstructed as wholly wooden, William of Newburgh’s account of stones removed from an inner wall may indicate a stone shell keep containing timber buildings.

Everyone who climbs Steep Hill in Lincoln has seen Lincoln Castle. It stands where William the Conqueror planted it in 1068, high on the old Roman upper city, its twin mottes and curtain wall commanding the whole plain. It is one of the best-preserved castles in England, and it still does the Crown's work — the Crown Court sits there to this day.

Almost nobody knows that Lincoln once had a second castle.

Down by the river, at the vulnerable (from a defensive point of view) south-eastern corner of the lower city, there stood for perhaps two or three generations a fortress called Thorngate Castle — castellum de Tornegat. It was not royal like Lincoln Castle (which at one time housed the sheriff, the constable/ castellan, and the bishop). Thorngate belonged to a family, held in their own right, and it existed in a state of quiet tension with the great royal castle on the hill. And then, in the space of a decade, it was pledged away as a bargaining chip in a civil war and demolished so completely that today we cannot even say for certain where it stood.

This is the story of that lost castle: of the family who held it, the war that consumed it, the forced marriages and shifting loyalties tangled around it, and the arguments that still divide historians about where it was and who really controlled it. It is, in miniature, the story of the whole terrible period we call ‘the Anarchy’ — and, as so often, it is a story with a woman at its centre whom history has almost entirely forgotten.

She paid a king five hundred marks for the right to be left alone. She outlived three husbands, presided over one of the most strategically significant castles in England, and left such an indelible mark on Lincoln Castle that a tower still bears her name nine centuries later. Yet Lucy of Bolingbroke remains one of the least-known powerful women of the Norman era – overshadowed, perhaps, by the very castle she helped to shape.

Today, I’m bringing this important but forgotten woman back into the light (as much as I can).