Nearly four years ago, I began writing a novel, set in the aftermath of the Norman conquest of 1066. Before I began to write, I spent six months sitting in the Bodleian library poring over books and journals to familiarise myself with the period. I soon realised that, apart from the story of the Battle of Hastings that everyone learns at school, I knew hardly anything about the impact of the conquest. I began to understand, too, how much of that impact is still with us.

By the end of the process, I had come to a slightly disquieting conclusion: we are still being governed by Normans.

Take house prices. According to the author Kevin Cahill, the main driver behind the absurd expense of owning land and property in Britain is that so much of the nation's land is locked up by a tiny elite. Just 0.3% of the population – 160,000 families – own two thirds of the country. Less than 1% of the population owns 70% of the land, running Britain a close second to Brazil for the title of the country with the most unequal land distribution on Earth.

Much of this can be traced back to 1066. The first act of William the Conqueror, in 1067, was to declare that every acre of land in England now belonged to the monarch. This was unprecedented: Anglo-Saxon England had been a mosaic of landowners. Now there was just one. William then proceeded to parcel much of that land out to those who had fought with him at Hastings. This was the beginning of feudalism; it was also the beginning of the landowning culture that has plagued England – and Britain – ever since.

The dukes and earls who still own so much of the nation's land, and who feature every year on the breathless rich lists, are the beneficiaries of this astonishing land grab. William's 22nd great-granddaughter, who today sits on the throne, is still the legal owner of the whole of England. Even your house, if you've been able to afford one, is technically hers. You're a tenant, and the price of your tenancy is your loyalty to the crown. When the current monarch dies, her son will inherit the crown (another Norman innovation, incidentally, since Anglo-Saxon kings were elected). As Duke of Cornwall, he is the inheritor of land that William gave to Brian of Brittany in 1068, for helping to defeat the English at Hastings.

The land grab was not the only injustice perpetrated by the Normans that has echoed down the centuries. William built a network of castles with English slave labour from which he controlled the rebellious populace by force. This method of colonisation and control was later exported to Ireland, Scotland and Wales, as the descendants of the Norman kings extended their empire from England to the Celtic nations. They taxed the poor harshly (the Domesday book is a tax collector's manual), deepening rural poverty to enrich royal coffers which were used to fight the continental wars that ravaged medieval Europe. Not without justification has one historian referred to Norman rule as a system of "medieval apartheid".

These days, I can't stop myself wondering what kind of country this might be now if William had lost at Hastings. Would we have been spared the aristocratic estates and the hereditary monarchs? Could the industrial revolution, even the empire, have happened in the same way without that intense concentration of land and power? Would the English be a less deferential people than they often still, frustratingly, are?

Questions like this can never be answered. But I think it's worth noting that in 2012, as in 1066, the ruling class still drink wine while the "plebs" drink beer, much of the country remains the property of a few elite families and the descendants of the Normans remain wealthier than the general population. Meanwhile, the nation as a whole is paying the price for the rapacity of a wealthy elite which feels no obligation to its people.

But it's worth noting something else too. The Norman conquest spurred a decade-long campaign of underground resistance by guerrilla bands across England – a story that is largely forgotten now. The Normans called these rebels the "silvatici" – the men of the woods, or the wild men – and they proved as hard to defeat as guerrilla fighters always are. Though the Normans were never expelled, the spirit of the silvatici can be traced throughout later English history, from the Peasants' Revolt to the tales of Robin Hood. Not everyone takes conquest lying down. Today's elites might like to take note.