So I was there, with all the rest of my fellow citizens, dressed in my best toga and cheering right on cue. I had proffered the obligatory little flask of perfumed oil – bought for the purpose at a special booth – and had it accepted by the attendant priest to be poured out on the altar at the proper time. I drew the line at paying a whole denarius to buy a withered branch of palm, though the streets around the temple were crammed with stalls of them.

I had learnt my lesson at last year’s sacrifice. Palms did not grow in this most northerly of provinces, and the ones that were imported in honour of the day were not only expensive, but so dry and fragile they had a tendency to crack if they were waved too hard. Moreover, some of them looked suspiciously like plants I recognized, carefully slashed to resemble the traditional frond – though I could be wrong, of course, I have never seen a proper palm tree in my life. So I’d ignored the traders this time and contented myself with finding a safe spot at the back of the temple court beside the colonnade where any lack of waving was inconspicuous. (We were in the Capitoline temple for the spectacle – the Imperial shrine was in a smaller building in a grove within the grounds, but there was not room for everybody on a day like this.)

However, I was quite prepared to cheer. The birthday ceremony gave us a real excuse for that. After the sacrificial animal was killed, its blood was offered up as an oblation to the gods, but when the immortals had imbibed their fill and the priests had made a ritual meal of the proffered entrails, the rest was generally taken off and cooked and shared out among the congregation as a feast. And judging by the animals lined up for sacrifice this year, there was going to be a generous distribution later on.

Of course there was always a competition on a day like this, with wealthy men attempting to impress the populace and trying to out-do their counterparts by offering the most perfect and expensive specimens. Quite a tradition had grown up locally – not one birthday offering, but a whole string of them: pure white calves and spotless goats and sheep, as well as the more humble pigeons, larks and doves. No doubt the donors hoped that news of their devotion and generosity would (given the fact that spies were everywhere) reach the Imperial ears.

Today, however, there was an even more impressive sight than usual. Someone had provided an enormous bull with gilded horns – a splendid creature, white from head to tail. One of the attendants had just appeared with it, and was leading it by a scarlet halter around its neck, at the head of a procession of civic dignitaries followed by a choir singing loyal hymns of praise and a young minstrel strumming on a lute. They moved towards the altar where the chief Imperial priest, the sevir Augustalis, stood awaiting them: a hooded figure in a reddish-purple robe, with the bronze diadem of his office barely visible beneath the hood. The sevir raised his knife. There was a sudden hush.

The temple was so crowded that it was hard to move, but a man on the step beside me – a citizen-trader whom I slightly knew – caught my eye and nudged me sharply in the ribs.

‘Just look at that, Libertus. A perfect sacrifice. That must have cost somebody an enormous sum!’ he whispered gleefully.

‘Almost as gigantic as the animal itself!’ I murmured in reply. ‘Someone hoping to impress the Emperor no doubt, and hoping for preferment at the Imperial court.’

‘Then I hope his prayers are answered,’ he retorted with a grin. ‘I shall feel he deserves it, if we get a piece of that.’

A stout man in a woollen toga, in the row in front, turned round and frowned warningly at us. ‘Don’t be so disrespectful. Don’t you know who gave the bull? It was Publius Atronius Martinus – that visitor from Rome. So just be grateful and keep your inauspicious comments to yourself. Suppose the priest had heard you, and all this had gone to waste!’ He snapped his head away and went back to watching the ongoing spectacle.

He had a point, of course. Any inappropriate noise or sight which reached the priest – or even a trivial error in the rite, like putting the wrong foot forward – would stop the sacrifice and the whole of the ceremony would have to start again, most likely with a different animal, since this one would be ill-omened by that time. But it seemed that all was well. The celebrant was pouring wine between the horns, and scattering the salsa mola – the sacred bread that only Vestal Virgins make – onto the creature’s head. Obviously the singing of the choir, which was designed to drown out inauspicious noise, had drowned us out as well. That was fortunate. Interrupting the sacred ritual today, and causing the Emperor’s birthday rite to stop, was likely to prove ill-omened in more ways than one.

My trader-friend, though, was undeterred by this. He made an unrepentant little face and mouthed silently at me, ‘Who is Publius Martinus?’

I was so startled that I almost answered him aloud, but I controlled myself and only muttered from the corner of my mouth, ‘You must have heard of him! He’s come to Britannia to collect a wife – the very Vestal Virgin who made the sacred cake. Though of course she’s now retired.’

He pulled his face down in a goggling mask. ‘A Vestal? Then he must be seriously rich.’

‘One of the richest men in Rome, apparently. So you’re wrong in one respect. Publius Martinus might have bought the bull, but not because he’s seeking patronage.’ I was still speaking in an undertone. ‘More likely a celebration that his bride agreed the match, especially since the girl has money of her own.’

He arched an eyebrow. ‘Well, of course she would have. Vestals all come from patrician families.’

Perhaps it had been an unnecessary remark, but I whispered stubbornly, ‘I meant that she wouldn’t have to marry just because she has retired. And it must have been her choice. Vestals are not like other women – they can make contracts and manage their affairs without the consent of any relative.’

He made a little face. ‘That’s true. Yet she can’t have met this Publius, if he comes from Rome. I wonder what made her decide to give up her special status and all the privileges that go with it? Perhaps she simply longed to have a family life – they say some women do.’ He sniggered mockingly.

I thought of my own wife, Gwellia, who would have loved to have a child. It made me answer rather acidly. ‘Is that so very strange? The bride has done her thirty years of service to the flame. She reached the anniversary only recently and now she’s free to do as she thinks fit. This Publius is a widower with three daughters and son – maybe she thought he looked a likely match.’

My neighbour nodded. ‘No doubt you are right. But if he is merely a visitor from Rome, why should he come here to Glevum and donate this sacrifice? There isn’t a Vestal temple anywhere near here.’

‘Her family lives nearby, apparently. I understand that she is on her way, herself.’

He looked impressed, then puzzled. ‘How do you know all this?’ he whispered. His expression cleared. ‘Oh, from your wealthy patron, I suppose. I’d forgotten that His Excellence Marcus Aurelius Septimus told you everything. I suppose as the most important man in the colonia, he’s likely to hear the gossip about everyone who comes. And . . . here he is in person.’ He nodded towards the group of celebrants.

My patron had joined them on the temple steps, together with the High Priest of Jupiter. They had emerged dramatically from inside the building, to the general amazement of the crowd, though there was really nothing remarkable in this: there was a hidden passage from the priest’s house to the shrine, especially to facilitate appearances like this. However, they were greeted with an approving roar and certainly they made an impressive sight. The priest of Jupiter was all in spotless white, while Marcus was resplendent in a toga with a broad patrician stripe, with a wreath of gilded laurel round his head and a heavy gold torque around his neck. These two were joined a moment later by a stout, bald, red-faced man who was clearly out of breath and had his wreath askew – presumably from unaccustomed scrambling through the passageway. He looked quite unimportant in comparison, but his toga’s purple edge announced him as a patrician of some consequence. Obviously this was Publius Martinus himself.

My neighbour nudged me sharply in the ribs. ‘Hardly a Greek statue, is he – if that’s the bridegroom, as I suppose it is? I hope the Vestal isn’t disappointed in her choice. When she sees him, perhaps she’ll change her mind.’

I shook my head. ‘From what I hear from Marcus Septimus, she’s formally agreed, and since she is a Vestal . . .’ I broke off and glanced around. I was half-expecting to be ‘shushed’ again, but I realized that other people were listening in to this. I was being indiscreet! So I said no more, except, ‘But shh! Let’s watch the ritual.’

The sevir was already plunging the knife into the bull and had seized a chalice in which to catch the blood. The beast began to stagger and was soon sagging at the knees and as it fell the crowd gave out a cheer. The trained attendants, the victimarii, fell upon it to disembowel it and hack it into pieces for the public feast.

‘I hear they give the creatures poppy juice to keep them quiet,’ my neighbour muttered as the noise died down again. ‘That would make sense, I suppose. Terrible bad omen if that ran amok and gored a priest or something.’ He nudged my ribs again. ‘Can you see it all from there, or is that pillar in the way? The hirospex is reading the entrails, by the look of it. Oh great gods, he’s hesitating! Is there something wrong?’

I stood on tiptoe to get a better view. ‘It doesn’t look like it. He’s put them on the altar fire, so they must have been all right, and he has decided that the omens spell good luck.’

My neighbour grinned. ‘Except for the poor animal, that is. Still, I won’t be complaining, if I get a decent slice.’

He was getting disapproving looks again, so I looked away and tried to pretend that he was not with me. In fact he wasn’t really. I had come here with Junio, my adopted son, but the pressure of the crowd had separated us as soon as we came in and he had been borne down nearer to the front, though he was still in sight. He was crammed up against a pillar not very far away.

He turned his head and saw me and flashed a smile. It was obvious he was enjoying this. It was only the second Emperor’s birthday festival that he had ever seen – last year had been the first; up to that time he had merely been my slave, and slaves were not generally brought into the temple court at feasts, but left outside waiting for their masters to come back. But now that I had freed him and adopted him he was a citizen and therefore entitled – and expected – to attend the rite.

I looked at him with pride. He wore the awkward toga effortlessly, as if he’d done so all his life, and looked more like a proper citizen than I did myself. Of course it was likely he did have Roman blood. He was born in a Roman household, before he was sold on to the trader that I got him from, so – though it is certain that his mother was a slave – his father was probably the master of the house. (The owner of a slave girl has exclusive rights to her – she is not permitted to consort with other slaves – and if a resultant offspring is not required by the house it will either be exposed and left to die, or passed on to a slave trader prepared to keep it till it is old enough to sell.) Of course Junio didn’t know his mother’s whereabouts or name – any more than she knew his, or what his fate had been; he would have been taken from her shortly after birth.

I wondered what she would think of him, if she could see him now, at nineteen years of age (or perhaps it was twenty, we could not be sure), a handsome married man with a family of his own. It was hard to remember, looking at him today, the piteous half-starved child that I’d purchased from the dealer all those years ago.

‘Are you going to stand there all day, citizen?’ The bald man who had frowned at us broke into my thoughts. ‘Only some of us would like to go and get positions at the feast.’

I had been so busy with my thoughts that I had not noticed that the crowd was shuffling forward by this time, towards the little grove within the grounds where the Imperial temple was. The sevir Augustalis was carrying the phial of blood, to pour out on the altar there; what remained of the entrails, the offal and the brains would be cooked on the altar fire and eaten as a ceremonial collation by the priest. The singers and musicians struck up again, but they were quickly drowned as the crowd – which had been silent – broke into tumultuous cheers and there was much enthusiastic waving of the fronds.

‘Well, citizen?’ The bald man was sounding more impatient now; I was blocking the access to the aisle.

‘A thousand pardons . . .’ I squeezed myself into the wall and allowed him to go past, hoping that the talkative trader would depart at the same time, so that I could link up with Junio again.

But my neighbour was not so easily deterred. He was forced forwards by the pressure of the crowd, but he turned to call to me, ‘I’ll go and do my duty by filing past the shrine, and then I’ll try to go ahead and save a place for you. They are already making preparations, by the look of it.’

He waved a vague hand in the direction of the court, where the dismembered bull’s carcass was being hauled away, taken off to the temple kitchens to be cooked. Already I could see a group of little temple slaves, at the doorway of the building where the attendants lived, ready with the trestles to set out for the feast.

‘Don’t trouble! There is my son – he’ll need a place as well,’ I shouted back. But I could have saved my breath. The man had already been borne off in the throng and my voice was lost in all the noise. I remained pressed against the wall until the crush had eased, and then made my own way down towards the court, looking out for Junio, who had likewise sidestepped from the crowd and was waiting beside a giant statue of the Father of the gods.

He emerged as I approached and fell into step beside me, his face alight with smiles. ‘A splendid ritual! Even better than last year.’ He gestured delightedly towards the Imperial shrine. ‘And what a culminating sacrifice! I hope the god Commodus appreciates the smoke. Myself, I am content to be a mortal and just enjoy the flesh!’

I flashed a warning look. This was a daring joke, if not outright indiscreet. Someone might have been close enough to hear. We were almost the last to join the file and the leaders of the original procession to the shrine were making their way back towards us by this time, so that my patron and his guest were almost parallel with us, though going the other way.

Junio saw the danger and added instantly, ‘But what a splendid basis for a feast. There will be enough for all – although there is a crowd.’

I nodded. ‘Enough for everybody here to have a piece – of one of the offerings, if not the bull itself! The temple slaves will see to that. Though it will take a little while for the later beasts to cook.’

He grinned at me. ‘So you are wise to have avoided rushing to the front. Trust you to think of clever things like that.’

In fact there was a considerable delay before we had made our duty visit to the shrine, ritually rinsed our faces and our hands and had our foreheads dabbed with altar-ash, so that we could join the crowd waiting at the long table in the court. My companion from earlier had reserved a space and was looking out for me, so Junio and I both went across and we managed to insert ourselves into the narrow gap and find a garland to put around our heads.

Just in time, in fact. The great dishes of cooked meat were being brought into the court, and the sevir muttered an incantation over them before they were taken and shared among the crowd. There is not much decorum at such a public ‘feast’. The attendant priest moved down one side of the table, offering the bowl and a muttered blessing to each man in turn. People seized a portion and gnawed it where they stood, followed by a quick swig from the communal cup, while people on the fringes queued to get a share. I ate mine and retired, being careful to keep my toga clean – the temple slaves would bring the bowls of rinsing-water for fingers afterwards, when the final prayer of dismissal had been said.

The trader, who had followed at my heels, licked the last scrap of cooked beef from his fingertips. ‘Well, that was very good. I suppose we must thank your Publius Martinus. Though no doubt he’ll have more than a taste of it himself – he and your patron will have the better bits. Along with all the rest of the councillors, I suppose. Just as they’ll have the best seats at the games this afternoon.’ He nodded towards Marcus and the official guests, who were on the dais at the front and had a proper place to sit.

I was about to murmur – diplomatically – that, since they were the ones who had provided all the beasts, of course the choicest portion would be reserved for them, but I was interrupted by Junio tugging at my sleeve.

‘Look,’ he said. ‘That visitor from Rome. It seems as if he’s leaving. And the final prayer’s not said.’

The trader goggled. ‘There’s been a message for him, by the look of it. It must have been important, to disturb him here.’ He pointed out the crimson-faced young courier who had fought his way unnoticed to the central dais, and was now escorting the Roman towards the outer gate. The crowd stood back to make way for them.

‘It’s no doubt to tell him that his Vestal Bride’s arrived,’ I said. ‘I understand he plans to present her to the crowd.’

Junio looked stunned. ‘You think he’d bring her here? A woman?’

‘Why not?’ I made a knowing face. ‘As a Vestal she’s entitled to attend.’

‘And claim her as his bride in front of everyone?’ The trader’s eyes were wide. ‘So we would legally all be witnesses?’

I shook my head. ‘I gather the formal nuptials will follow afterwards. The bride’s uncle is arranging another banquet at his home – no doubt an old-fashioned wedding with vows at the family altar. There’ll be witnesses enough. Everyone important is likely to be there.’ I was aware of people listening as I spoke, but I was not concerned about discretion now. If Publius had gone to fetch the Vestal, as it looked as if he had, the whole of Glevum would know it very soon and I was rather proud to be the first to break the news.

But it seemed that I was wrong. Though we waited an interminable time Publius Martinus did not come back again. The official party looked at first bemused, and then increasingly impatient, until – after a little whispering among the priests – the sevir rose and spoke the words that showed the feast was at an end. The musicians struck up again, the important guests filed out, and the rest of us were free – at last – to drift away.

As I walked out of the enclosure with Junio at my heels a hand fell on my shoulder. I turned around, to find the trader looking quizzically at me. ‘So it seems that you were misinformed? There is no Vestal Virgin after all.’

A palm-frond trader was packing up his stall and must have overheard. He sidled up to us. ‘You haven’t heard then, citizens? Well, I’m not surprised. The runner said that he’d been told not to give the message till the man came out here, away from public ears. It would have been a dreadful scandal wouldn’t it, if they’d announced that the bull of sacrifice had proved to be ill-omened after all, just at the moment when you’d all eaten it?’

I rounded on him. ‘What do you mean, ill-omened? What has happened now? Did that messenger bring news about a problem of some kind?’

‘There was a proper fuss. Boy had come running with a message all the way.’ He bared his snaggled teeth into a yellow grin. ‘That Publius’s servant was waiting by my stall and when the man came out, I heard every word they said.’

I saw where this was leading, and I reached into my purse. ‘A sestertius if you tell us, and it proves to be the truth.’

The stallholder took the coin I offered him, and tried it in his teeth. When he was satisfied he grinned at me again. ‘Well then, I’ll tell you, citizen. You’re right in one respect. There was a Vestal Virgin – but she has disappeared. That fat Roman has gone to look for her.’