Not that Caesar’s achievements were insignificant. He had greatly increased the Romans’ knowledge of Britain. He polarised the British, especially those in the south, as pro- or anti-Rome, a division which suited Rome’s diplomats and traders very well.

Under the first emperors, however, Britain’s isolation continued. Augustus, conservative, consolidating and reforming, did not have ambitions that stretched so far - and the loss of three of his legions in a dark German forest did nothing to spur him on. In the reigns of Augustus’s successors peaceful contact between the empire and Britain was assisted by the calming, pragmatic policies of Cunobelin, a local king the Romans called Cymbelinus. Even in these times, however, tentative plans for the invasion of Britain had been drawn up. Caligula, though unstable, was certainly no fool, and nor were his generals. He had got as far a building a harbour with a lighthouse at Gesoriacum for the purpose.

But now Cunobelin and Caligula were dead, and a new generation on both sides of the Ocean had new ambitions.

It was only two years ago, in the chaos following the murder of Caligula, that Claudius had been raised to the throne by the Praetorian Guard, bodyguards of the Emperor. Since then, despite proving a surprisingly competent ruler and a fast learner, Claudius had faced opposition from the army, the Senate, equestrians and citizens alike. Military power was the key, as always, and what Claudius needed above all was a military triumph - and all the better if he could be seen to outdo even the exploits of Caesar himself. The predatory antics of the Catuvellaunian princes in Britain gave him the perfect pretext.

As for Narcissus, he would survive only so long as he served his Emperor’s ambitions, even while furthering his own.

Narcissus had been born a slave. With time, relying on his wits and his charm, he had made himself so invaluable to a succession of masters that he had been able to work his way into the households of the emperors themselves - and in Claudius, first emperor since Augustus able to recognise a sharp intellect as the most valuable weapon of all, he had found a true patron. It was Claudius who had freed him. Under Claudius, though his title was merely correspondence secretary, epistula, Narcissus had been able to use his position between Emperor and subjects to accrue power. He had amassed wealth of his own. He had even become a player in the most dangerous game of all, the domestic politics of the Emperor’s household, allying himself with Claudius’s latest wife, Messalina, in the endless intrigues of the court.

In Rome Narcissus was a powerful man, then. But now fate had brought him across the Ocean, beyond civilisation altogether. And, worse than that, it had cast him alone among soldiers.