‘Richard II tried first being a Good King and then a Bad King without enjoying either very much. Then being told he was unbalanced, he got off the throne whereupon his cousin Lancaster (spelt Bolingbroke) quickly mounted the throne and said he was Henry IV, Part 1.” This, anyway, is how it goes in 1066 and All That, the classic parody of garbled schoolroom rote-learning. And while Helen Castor, a historian of great nuance and meticulous scholarship, would not put it quite so baldly, this remains pretty much the through-line of her luminous 600-page study of the Plantagenet cousins who between them generated the plots for three of Shakespeare’s history plays.

The Hart of Castor’s title is Richard II, who came to the throne at the age of 10 in 1377 and never stood a chance. His early accession was a consequence of his father’s death the previous year. Edward, the Black Prince, had led England to its first big win in the hundred years war at the Battle of Crécy, after which France gave up a third of itself to England. And now in his magnificent place came this thin-skinned, spoilt, effeminate boy. Harts – male deers – are generally depicted in heraldry as beefy, bulky, russety animals with a forest of antlers. But Richard chose a white hart as his personal emblem instead and commissioned artwork, which features on Castor’s cover, showing a pale animal, as slender as a greyhound, tethered to the ground by a heavy golden chain.

It is tempting to see that chain as representing Richard’s bullying uncles, who insisted on telling the boy king what to do. The results were disastrous. In the first three years of the reign there were four parliaments, and by 1381 the peasants were revolting, to use another cliche of the mid-century schoolroom. The immediate cause was the imposition of a poll tax, to be levied on rich and poor alike. But there were, as always, bigger, deeper discontents at work. When Wat Tyler and his men swept in from Kent and Essex and set fire to grand London buildings, they were giving notice that feudalism was finished and nothing less than a redistribution of the church’s and nobility’s massive wealth would do. To get their point across, they killed the archbishop of Canterbury and destroyed the Savoy Palace, home to John of Gaunt, Richard’s virtual regent who doubled as the Duke of Lancaster. Tyler was rewarded by having his head stuck on London Bridge.

There are a lot of decapitated heads in Castor’s story, as well as spilt guts and slow hangings, not to mention less judicial but equally excruciating deaths from dysentery (it carried off the Black Prince) and bubonic plague. It was perhaps to remove himself from this rancid fleshiness that Richard set about eliminating all traces of the corporeal from his daily life. He had a horror of personal stink and built a bathroom that was a wonder of the world. When one London citizen wanted to express frustration at the court’s ruinous extravagance, he suggested that the king “should stay in his latrine for the rest of his days”. Bog off, in other words. To clothe his etiolated body, Richard insisted on elaborate costumes at extraordinary expense. Castor is very good on the rustling silks, the sheeny leather, the weightiness of the gold cloth in which the king decked himself, in the process making a silent statement about his distance from the common herd.

Then, of course, there is the intriguing fact that Richard’s 12-year marriage to Anne of Bohemia remained childless. On Anne’s death in 1394 he seemed positively relieved that his new wife was to be Isabella of Valois, who was only six years old and travelled with her dolls. In effect, the reluctant bridegroom had been given a free pass for seven years before being recalled to the marriage bed. He had a favourite, too, a man called De Vere, whom everyone whispered about.

This failure to be anyone’s idea of a warrior chief or wise father made Richard deeply unpopular, but getting rid of a divinely appointed king involved some complicated mental gymnastics: in effect it would mean suggesting that God had got it wrong. Crunch time came with the death of John of Gaunt in 1399. By rights, the Duke of Lancaster’s vast estates in the north-west of England should now pass to his son Henry Bolingbroke. But the previous year Richard had sent Henry into lengthy exile. Instead of keeping the Lancaster lands safe until his cousin was able to claim them, Richard nabbed them for himself. This left Henry, the Eagle of Castor’s title, no choice but to come storming back to remove Richard from the throne and claim it for himself. Richard’s final fate is unclear, but the most likely scenario is that he was left to starve in Pontefract Castle.

Things didn’t immediately get better under the newly minted Henry IV, which in many ways is Castor’s point. England’s problems were endemic and enduring and no new king was going to be able to magic them away. The weather turned horrible, the Black Death returned for an encore, and the peasants, if not revolting, were hardly in a mood to be helpful. Even the holy oil used to anoint Henry at his coronation gave him lice, making his hair fall out. The country would have to wait for another 14 years until Henry’s son, Shakespeare’s Prince Hal, succeeded to the throne and the age of heroes could begin again.