In Power, Professor Robert Bartlett lays bare the brutal framework of the medieval class system. Inequality was as part of the natural order, the life of serfs little better than those of animals, the knight’s code of chivalry more one of caste solidarity than morality. The class you were born into determined who you were.

There were three classes, or estates: those who pray (the clergy), those who fight (the aristocratic warrior class of knights) and those who work (everybody else – in practice, usually serfs on a knight’s estate).

Robert looks at the penalties to be paid by serfs who ran away, and describes the harsh laws which protected the hunting rights of the king in the vast forests of medieval Britain.

Medieval lords were not so much landlords as warriors. Their land was given to them by the king precisely because they were warriors and supported him in military campaigns. Fighting was in their blue blood.

These knights followed the international codes of chivalry – a word today synonymous with gallantry and noble behaviour. Knights could behave nobly, but it was generally towards their own class.

To hold such a violent society together was no easy task. It would need divine help. As Robert explains in Westminster Abbey, that is just what medieval kings had – at the ceremony of the Coronation the new monarch was anointed with holy oil, signifying his divinely sanctioned right to rule.

But this rigid order was fatally undermined by the Black Death, creating a labour shortage which resulted in the serf achieving higher wages and geographical mobility. At Blackheath and at the Tower of London learn how the drama of the Peasants’ Revolt unfolded, when the despised third estate – those who work – began to taste a new freedom.