Nectovelin bellowed his frustration, drew a dagger and began to run at Claudius. But the Emperor, recovering from his shock, called for his guards: ‘Custodiae!’

The first to respond were the two senior Romans of the day before in Camulodunum, the impressive commander and the Greek - though the commander’s armour was half undone, and the Greek wore a nightshirt. The commander, unarmed, unhesitating, hurled himself at Nectovelin’s legs and brought him crashing to the ground. Nectovelin struggled but the Roman, younger, just as heavy, was on his back, and in an instant he had taken Nectovelin’s own dagger and pressed it to his throat.

More soldiers burst into the room. Agrippina didn’t hesitate. She grabbed the Greek, easily twisting an arm behind his back, and cut his cheek with a savage swipe of her knife. The Greek screamed, his voice high, like a distressed sheep’s.

The Emperor seemed more concerned for the Greek’s fate than his own. He took a step forward. ‘Narcissus!’

‘Stay back,’ Agrippina snapped in Latin. ‘Let Nectovelin live. Or this one dies before your eyes.’

The crowded granary had become a tableau - the Emperor, Agrippina with Narcissus, Nectovelin with his own blade cutting into his flesh, and the guards staring wildly, their swords drawn. One of them had Cunedda in a bear-hug.

The Roman on the ground looked up. ‘Emperor,’ he hissed. ‘Let me finish off this fat pig.’

Claudius was a small, middle-aged man. The single step he had taken was uneven, a limp, and his mouth open and closed, gulping like a fish, as he took in the situation. The rumours in Gaul were that Claudius was a weakling, perhaps even deformed, the runt of the imperial litter. He wore thick socks, comically; perhaps he had poor circulation too. But he was an emperor, and after that first moment of shock he stood straight, and his voice was firm. ‘Let him up, Vespasian.’

‘Sir—’

‘Let him up! I am in no danger now.’ He glanced at one of the soldiers. ‘We will deal with the issue of my personal security later, Rufrius Pollio.’ The man, perhaps the commander of the guard, cowered. ‘But I would not lose my secretary to these grubby thugs. Let him up, I say.’

The Roman commander, Vespasian, clambered reluctantly off Nectovelin. He hauled the Brigantian to his feet with a massive hand at the scruff of his neck, and he kept a grip on Nectovelin’s arm. ‘One move out of you, you ugly bastard, and I’ll slit your throat no matter what the Emperor says.’

Nectovelin had not taken his eyes off the Emperor. Agrippina kept her knife blade at the throat of the Greek, Narcissus.