After Nero the imperial succession was bloody, and a civil war broke out between rival claimants. For Agrippina it was a terrifying time, a throwback to the days of Julius Caesar when strong men backed by private armies had battled for power. Indeed the still-young empire was nearly destroyed in the process. The crisis was resolved when an old acquaintance of Agrippina’s, Vespasian, came out of retirement to become the third emperor in a year. With the competence and ruthlessness he had once shown in Britain, he soon restored order in Rome.

Meanwhile under Cartimandua, who seemed to be emulating Cunobelin of the Catuvellaunians, Agrippina’s people the Brigantians, still independent of Rome, grew rich on trade with the new province to the south. There was a flowering of culture, she sensed from the letters she received from home, of literacy and music and art and education. But sprawling Brigantia was only ever a loose federation, difficult to control, and when even the queen’s husband Venutius grew restive, unease about Cartimandua’s Roman policy penetrated even her own bedroom. In the end Cartimandua had a reckless affair with her husband’s armour-bearer, and Venutius’s fury ignited civil war.

The Romans, under Vespasian’s strong governors, rescued Cartimandua, and then moved into Brigantia for good, pinning it down under a network of forts and roads. They established a legionary fortress in Agrippina’s old birthplace of Eburacum. After that, a generation after their first landing in south-east Britain, the Romans pushed further north still, into the misty highlands of Caledonia.

Meanwhile Agrippina’s family was denuded of males by all this turmoil, and lacked heirs. Aged fifty she found herself bequeathed a majority stake in the family’s quarrying business. Agrippina had no interest in overseeing this herself - but Cunedda had had a son, born in Camulodunum. Through an exchange of letters she transferred her holding to him, a last gesture to a long-dead lover.

Under the solemn calm of Vespasian’s rule, Agrippina watched over her growing children. She made fitful efforts to recover Nectovelin’s Prophecy, which Claudius had lodged in the vault of the Sibylline oracles, but these came to nothing. And she tried, even as she turned them into strong Roman maidens, to tell her daughters something of where their blood came from. She told them long stories from her own childhood of ancestral Brigantians, who had ruled with bronze or stone, in ages when only sheep had ruled Rome’s seven hills.

But her body betrayed her. A racking cough grew steadily worse, until she woke one morning to find she had been coughing up blood.