Part of Pharos Island, together with the heptastadion, formed one enormous arm around the Great Harbour. On the shore side, where we were, lay various wharfs; some encircled sheltered docking areas. Then away to our right, near where we were staying with Fulvius, another promontory called Lochias completed the circle. On this famous peninsula, we knew, many of the old royal palaces stood, the haunt of Ptolemies and Cleopatras long ago. They had had a private harbour and a private island they called Antirrhodus because its gorgeous monuments rivalled Rhodes.

The main part of Pharos Island turned in the opposite direction to form the sheltering mole around the Western Harbour. This was even bigger than the Great Harbour, and was known as the port of Eunostos, with its inner basin Kibotos, supposedly all man-made. Way out of view behind us, on the other side of the city, was Lake Mareotis, a huge inland stretch of water where yet more wharves and moorings served the export of papyrus and other commodities that were produced around the lake.

For Romans all this was a shock.

‘We are so used to thinking that Rome is the centre of the trading world!’ Helena marvelled.

‘Easy to see why Alexandria was able to pose such a threat. Just suppose Cleopatra and Antony had won the Battle of Actium. We could be living in a province of the Egyptian Empire, with Rome just some unimportant backwater where uncultured natives in crude tribal garments insist on speaking Latin instead of Hellenic Greek.’ I shuddered. ‘Tourists would rush straight through our town, intent on studying the curious civilisation of the ancient Etruscans instead. All they would have to say for Rome is that the peasants are rude, the food is disgusting and the sanitation stinks.’

Helena giggled.’ Mothers would warn impressionable daughters that Italian men might look handsome, but would get them pregnant then refuse to leave their Campagna market gardens.’

‘Not even if the girl’s uncle offered the fellow a good job in a papyrus factory!’

As we turned back for home, we walked by an absolutely enormous Emporium that made the central warehouse in Rome look like a collection of cabbage stalls. Also beside the waterfront we found Cleopatra’s Caesarium. This monument to Julius Caesar, at the time still unfinished, had become the place of refuge where the Queen hauled up the wounded Mark Antony to die in her arms after he tried to kill himself in his own refuge, another impressive monument by the harbour which was called the Timonium. Then the Caesarium was the scene of her own suicide as Cleopatra pipped the gloating Octavian’s hopes of flaunting her in his ceremonial Triumph. For that alone I liked the girl. Unfortunately Octavian turned the Caesarium into a shrine to his own dreadful family, which spoiled it. It was guarded by enormous old red granite obelisks, which we were told he had brought from elsewhere in Egypt. That was one advantage of this province. Exotic outdoor ornaments littered the place. Had these obelisks not been such dead weights, Augustus would undoubtedly have shipped them off to Rome. They were begging to be used in trendy landscape gardening.

We gazed at the Caesarium, and felt the pang of standing next to history. (Trust me; it is extremely similar to the pang of badly wanting a sit-down and a drink of cold water.) We found a giant sphinx against whose lion paw we could lean weakly until guards chased us off. Helena was at pains to assure me that Cleopatra’s mystique had derived not from beauty but from wit, vivacity and vast intellectual knowledge.

‘Don’t disappoint me. We men imagine she bounced about on scented satin pillows, wildly uninhibited.’

‘Oh Roman generals like to think they have seduced a clever woman. Then they can fool themselves they have done it for her own good,’ Helena mocked.

‘Anything less frigid than the average general’s wife would have seemed hot stuff to Caesar and Antony. An hour of Cleo throwing her sceptre at the ceiling and doing erotic back-somersaults would pass pretty pleasantly.’

‘And the Queen of the Nile could tickle their fancies while simultaneously showing off how she had read natural philosophy and was fluent in foreign languages.’

‘Linguistic ability was not the kind of kinky taste I meant, Helena.’

‘What - not even to shriek, “More! More, Caesar!” in seven languages?’

We went home for a rest. We would need energy that evening. We had to endure a formal dinner with a dignitary. That was nothing.

Before it began, according to my uncle’s house rules, we had to persuade Julia and Favonia to go to bed much earlier than they wanted to -and stay there.

IV

Cassius had thrown himself into the evening. Most of it worked. The decorations and some of the dishes were superb.

He served grilled fish in Sauce Alexandrian. Although Cassius saw it as a compliment to Egypt, I reckoned any local guest was bound to feel this recipe fell short of his mother’s cherished version. Cassius was asking to be informed that stoned damsons were now a cliché and everyone who was anyone used raisins in their sauces . . . On the other hand, Cassius whispered that he could never have trained the cooks in time to do fine Roman cuisine. He was afraid that the pastry chef would knife him, if asked to try. Worse, he suspected that the chef had sensed the possibility of being asked to change his repertoire, and might already have poisoned the fried honey cakes. I suggested Cassius should eat one to check.

The Librarian did come, though he was late. We had to endure an hour of Fulvius getting agitated as he thought he had been snubbed. Then, while the man shed his shoes and was made comfortable, Fulvius pretended to us that arriving late was a custom here, a compliment that implied a guest was so relaxed he felt time was of no consequence ... or some such waffle. I could see Albia staring, wide-eyed; she had already been startled by my uncle’s outfit, which was a loose dining-robe of the type called a synthesis, in vivid saffron gauze. At least the Librarian had brought Fulvius a gift of potted figs, which would solve the dessert problem if Cassius keeled over after my pastry test.

His name was Theon. He looked acceptable on the surface but his clothes were a fortnight overdue at the laundry. They had never been stylish. His workaday tunic hung on a thin frame as if he never ate properly and his beard was sparse and straggly. Either he was too poorly paid to live up to his honourable position, or he was a natural slob. As a natural cynic, I presumed the latter.

At dinner, Cassius hung us all with special garlands then positioned us carefully. It was intended we should have three formal courses, though service was curious and distinctions became blurred. Still, we ploughed diligently through the correct rota of conversation. The appetisers were given over to my party’s voyage. Helena, acting as our spokesperson, gave a humorous oration on the weather, the mercenary ship’s captain and our stop-off in Rhodes - with its highlight of looking into the gigantic pieces of the fallen Colossus and seeing the stone and metal framework that would have held it upright, but for the earthquake.

‘Do you suffer many earthquakes here?’ Albia asked Uncle Fulvius in extremely careful Greek. She was learning the language and had been instructed to practise. Nobody would think that this grave and neat young girl had once roamed the streets of Londinium, an urchin who could spit ‘get lost, you pervert!’ in more languages than Cleopatra elegantly spoke. As adoptive parents we viewed her proudly.

Helena had created a Greek phrasebook for our foster-daughter, including the question on which Albia had sweetly ventured as an icebreaker. I regaled the company with further examples. ‘The next continues the volcanic theme: Please excuse my husband farting at the dinner table; he has a dispensation from the Emperor Claudius. A footnote reminds us this is true; all Roman men enjoy that privilege, courtesy of our frequently maligned ex-Emperor. There was a good reason why Claudius was deified.’