‘You are going to attack, aren’t you?’ I asked.

‘Next week it will be May,’ Agrippina replied. ‘I tell you, Parmenon.’ She looked over her shoulder satisfied that the guards were in position. ‘If I do not move now, this time next year none of us might be here. I don’t fancy another long period of exile. Are you with me, Parmenon?’

‘That’s a stupid question, Domina. If you fall we all fall with you.’

‘You could retire,’ she smiled. ‘Buy a villa or farm out in Campania. Marry some pleasant girl, have children, raise a son.’

‘A son like Nero, Domina?’

‘You have it all wrong.’

She rose, patted me on the shoulder and walked away.

I didn’t have it wrong but Agrippina was intent on proving herself right. She moved slowly, carefully, distancing herself from the Emperor. She began to act like a recluse but took me more and more into her confidence. I once saw a wolf in the arena, which, although famished and dangerous, only attacked when it was sure which of his intended victims was the weakest. Agrippina was the same. She perched above Claudius’s court and watched carefully. Pallas was her man, body and soul, and she thought the same of Burrus and Seneca; but Narcissus was now her enemy. She studied them carefully one by one, weighing their worth, all the time refusing to rise to Claudius’s baiting.

It was late summer before she was finally ready to strike.

I was told to stay up late one night and act as door-keeper, whilst the slaves and servants were dismissed to their quarters. Agrippina was evidently expecting a visitor, but in fact, it turned out to be two. I recognised one immediately: the fat-faced, small-eyed, balding court physician Xenephon. The other was a diminutive, pale-faced, red-haired woman with strange green eyes and heavily painted lips. She was dressed in tawdry finery except for the pearls around her neck which were genuine enough. She was Locusta, the descendant of a long line of famous poisoners. After Locusta had been seen and dismissed, Xenephon was treated to the pleasures of both board and bed. Agrippina had discovered that the Emperor had secretly changed his will. He’d also confided to this treacherous physician how tired he was of Agrippina’s ambitions. Now that both Xenephon and Locusta were in Agrippina’s net, they would find it impossible to extricate themselves.

Ominous portents appeared in the city: rumours of a flaming comet; showers of blood in the forum; a lightning strike at the Praetorian camp; a swarm of bees settled on the Palatine. Doors to the temple of Jupiter opened and closed of their own accord. The birth of a hermaphrodite was reported, as well as a pig born with the claws of a hawk. It was the usual farrago of nonsense. Some were natural phenomena, others sprang from Agrippina’s fertile imagination. Claudius became frightened, withdrawing more and more into the palace, but Agrippina followed like a hunting leopard. I had no idea how and when the attack would begin but, from Agrippina’s air of subdued tension, I sensed that if she had her way, Claudius would never welcome another new year.

On the night of 12 October, Agrippina invited her husband to a supper party in one of the palace banqueting halls. Claudius arrived with the four women who had become his constant companions: a blonde Syrian; a huge negress with purple lips; a slim Jewess whom Claudius loved to have pinch and slap him; and finally, a bronze-skinned Egyptian. The sole task of these women was the sexual gratification of the Emperor, a welcome relief for Agrippina as it distracted his attention from her. On that particular evening Agrippina was charm personified. Nothing was too good for her husband. An artificial ceiling had been created above the banqueting hall, which opened to shower full-blown roses and perfumed water on Claudius and his small coterie of guests. A troupe of Ephesian dancers mimed the marriage of Psyche and Cupid to the sound of flutes and pipes. Once this was finished, the imperial taster Helotus brought in the hors d’oeuvres, a bowl of deliciously cooked mushrooms, Claudius’s favourite dish. I was standing behind Agrippina’s couch as Helotus tasted the mushrooms. Agrippina nibbled at the side of the dish and smilingly invited Claudius to partake of the bigger ones. Claudius ate them with relish and asked for more.

‘Where is Narcissus?’ Claudius raised his head. ‘He should be here. He loves mushrooms.’

‘He’s gone to the baths at Sinuessa,’ Xenephon said. ‘He’s suffering the symptoms of early dropsy.’

Xenephon caught Agrippina’s eyes, smiled and glanced away. The removal of Narcissus was essential to Agrippina’s plans. More mushrooms were brought, but Agrippina became anxious when Claudius, helped by his escort, eased himself off the couch to go outside to purge his stomach and then on to the latrines to empty his bowels. When the old glutton returned hale and hearty, Agrippina’s agitation grew. I could detect the signs: the movement of her head as if to ease a crick in her neck, the quick false smile. I leant over to whisper ‘Relax,’ when Claudius squirmed on the couch, clawing at his stomach. He half raised himself but fell back with a groan; his face had turned livid, his big tongue lolled out, he shivered, and his teeth chattered. Xenephon sprang up and came over.

‘Oh, Divine One!’ he exclaimed. ‘What is the matter?’

The rest of the guests fell silent.

‘Quick! Quick!’ Xenephon gestured at Agrippina. ‘The Emperor has eaten something which has upset his stomach. It’s best if he purges himself.’

A silver bowl and a peacock feather, its tip soaked in perfumed oil, were brought. Xenephon, helped by Agrippina, thrust this into Claudius’s mouth, attempting to tickle his throat and make him vomit. Claudius was immediately sick and, wiping his mouth, pronounced that he felt better; but within minutes the cramps had returned.

‘The Divine One must rest.’

Agrippina got to her feet, gesturing at the slaves to lift the Emperor from his couch. With me and Xenephon trailing behind, Agrippina and her husband retreated into their private apartments. Once the Emperor was laid on the bed, the slaves dismissed and the doors locked, Agrippina turned on Xenephon.

‘You said the poisoned mushrooms would be enough.’ She glared, totally ignoring her husband’s groans and retching on the bed.

Xenephon, trembling with fright, spread his hands. ‘Excellency, he must have taken antidotes, otherwise what was on the tip of that feather alone would have been enough to kill him outright.’

Agrippina glanced at me. ‘Look, Parmenon. This is like the death of Tiberius all over again.’ She pointed to the bed. ‘If Claudius recovers, we will all die.’

She began to organise the palace guards, and no one was allowed into the chamber. For the next two days Agrippina allowed false messages to be disseminated, stating that the Emperor was recovering from a stomach ailment and all would be well. Seneca and Burrus were brought into the plot. A hand-picked cohort of the Praetorian Guard took up residence in the courtyard. Agrippina never left her husband’s side and for two whole days that old body, rotten with gluttony and excess, tried to fight the effects of the poison. Sometimes Claudius would attempt to rise but the cramps kept him prostrate. Agrippina scrupulously banished all food and drink from the chamber so as to dispel any suspicions that the Emperor was being poisoned. Instead she just waited for the full effects of that first poisonous meal to wreak its effect.

The Emperor, his body wracked by vomiting, retching and violent diarrhoea, gradually weakened. He lost all sense of feeling, muttered about the cold and, on the morning of the second day, finally slipped into death.

Xenophon checked the corpse scrupulously, whilst Britannicus and Octavia were brought to an antechamber and kept there under close guard. Seneca and Nero were summoned to prepare the speech the heir would give to both the Praetorian Guard and the Senate. By mid-morning Agrippina was ready, and the palace doors were thrown open. Nero, with Seneca on one side and Burrus on the other, emerged onto the steps of the courtyard whilst Agrippina’s claque amongst the waiting crowd began the whisper, ‘Claudius is dead! Claudius is dead!’