The old man, Orosius, called after them, 'Do you even know the name of the city your kind is despoiling, you barbarians? Do you even know where you are?'

Wuffa looked back. 'This is Lunden. What of it? Who cares?'

The old Briton they had saved continued to shout insults, but the young men walked away.

On Wuffa's last day before he set off for Reptacaestir, a scop, a wandering poet, called at his home village. Coenred welcomed the ragged wanderer, fed him meat and ale, and assigned him the village's one precious slave for his comfort.

The village itself was homely, a huddle of timber-framed houses with smoke streaming from their thatched roofs. To the wheeze of the smiths' bellows the people went about their chores, talking in grave rumbles about business, chasing children and chickens. The more substantial houses had doorposts carved with entwined decorations, brought over the sea from the old country, a reminder of home. Around the halls were rougher huts with sunken floors, workshops for weaving, iron-working and carpentry, and beyond that were pens for the chickens, sheep and pigs. There was no street planning, as Wuffa had seen in the ruins of Lunden; the houses grew where they would, like mushrooms.

The village of Coenred and his kin was one of hundreds of such settlements spread in a great belt around the walls of Lunden. There was still enough wealth flowing, through the old docks and the new trading area called Lundenwic, to make Lunden valuable to Aethelberht and his underkings – that and the prestige of owning the huge carcass of what had been the most valuable city in Britannia. So people were drawn here, to live and work.

As evening closed in, the village's largest hall filled up. A fire blazed in the hearth, and the people gathered on benches and patches of straw-covered floor, their faces shining in the firelight like Roman coins. Many had taken the opportunity of the scop's visit to dress in their best, in clean, brightly-dyed clothes adorned with brooches, with necklaces of amber and bits of old Roman glass, and silver finger rings. The men had their seaxes at their waists, the bone-handled knives that gave the people their name. Many of the older folk flexed fingers and joints riddled by arthritis. Coenred, at forty-four, was one of the oldest.

Wuffa was related to almost everybody here; this was his family.

As the ale circulated the mood mellowed, and the laughter began. At last the scop stood up, with his traditional command: 'Listen!' He looked a little unsteady on his feet, but when he spoke his voice was powerful and sonorous. 'Hear me, gods! I am crushed by longing and regret. I wake in mist-choked air, and labour the soil of a dismal island. For I have followed my lord across the sea, and my home lies far away. The fields of my fathers are drowned by the sea. My children grow stunted in murky dark. For I have followed my lord across the sea, and my home lies far away…' As he warmed to his theme, a typical Saxon lament of loss and regret, the adults, swaying gently to the rhythms of his speech, joined in the line of the chorus.

That bishop was right, Wuffa thought. The Saxons were a gloomy lot. Then the ale started to work on him, softening his thoughts. He drifted into the comforting, sombre mood of the hall, murmuring along with the other men to the scop's dismal chorus, and dreaming of the pale thighs of the British girl, Sulpicia.

As night fell the eerie whiteness of the comet was exposed, as flesh falls away to reveal bone, its unearthly light penetrating the warmth of the hall.

V

Reptacaestir was a Roman fort, with immense walls and curving towers laid out according to a cold plan. It was like a tomb of stone. A greater contrast with the warm village of Coenred could hardly be imagined.

Alongside Ulf, Wuffa led his horse cautiously into the bustling port. The land here, close to the east coast, was dead flat under a huge, washed-out sky. Wuffa could smell the sea. They dismounted and stood uncertainly among crowds of Norse and German traders. Huddles of British refugees sat quietly on the ground, waiting for their ships.

'Ah, here you are.' Bishop Ammanius approached, a calculated smile on his broad, well-fed face. He wore more practical clothes than in Lunden: a coarse tunic, leather trousers, sturdy boots, a cloak. He was accompanied by a couple of young monks, heavily laden with baggage, their tonsured scalps bright pink. Ammanius called them 'novices' and barely gave them a second glance.

With him, too, was the British girl Sulpicia. Wuffa couldn't take his eyes off her. The sturdy, almost mannish clothes she wore today set off the delicate beauty of her face. She looked strong, he thought, strong and supple. She was British, she was Christian, she was different- and yet his body cared nothing about that.

He approached her. 'So you came,' he said.

She returned his stare. 'My father is safely dispatched to Armorica. I have some skills in writing and figuring; I will be of use to the bishop, I think.'

'And you will be with us for fifty days, perhaps more. How lucky for me.'

'We have a holy mission to fulfil,' she said, faintly mocking. 'That should be uppermost in our thoughts.'

'Ah, but I'm no Christian.'

'Then we have nothing more to say to each other.' She turned away. Her hair blew across her face in the soft breeze off the sea. She smiled.

The game is on, he thought warmly.

Ammanius insisted on walking them around the port. Within the walls of the old Roman fort, timber houses stood on the plans of ruined stone buildings. On a low mound at the centre of the fort he pointed out a complicated series of foundations and stumps. 'They built an arch here to celebrate the triumph of Claudius. This was the very first place the Romans landed.' He took a deep breath of sharp, salt-laden air. 'Why, Christ was barely down from His cross. Later the arch was demolished to help build the walls of the fort, to deter you hairy-arsed raiders and your bee-sting assaults on the coast. But you came even so. And then a king called the Vortigem fought and won a great battle against you, here on this very spot…'

Britannia had been a Roman diocese, with its capital at Londinium. The British had thrown off the imperial yoke by their own will, through rebellion. The diocesan authority collapsed, but the four sub-provinces survived. The provincial states were successful. The old towns and villas continued to function; taxes continued to be collected. Literate and Christian, the British even exported their Roman culture to the peripheries of Britain, to the west and north and to Ireland, places where the eagle standard had never flown.

But in an absence of power, strong men took their chances. Here in the south-east, a man called Vitalinus struggled to the top of a heap of town councillors and military commanders. With dynasty in mind he married the daughter of Magnus Maximus, one of many British pretenders to the imperial purple in the old days. Soon he was calling himself 'the Vortigern', a word that meant something like overking. He had been the Aethelberht of his day.

But, lacking trained troops, Vitalinus hired Saxon mercenaries for protection. The Saxons beat off attacks from the Picts from the north. But when plague struck southern Britain and Vitalinus's tax revenues collapsed, the unpaid Saxons rebelled.

Ammanius said, 'At first Vitalinus fought well. His son, Vortimer, won that great victory, here at Reptacaestir. This was, oh, about a hundred and fifty years ago. Your grandfather's grandfather might have fought in that battle, Wuffa! I doubt your poets sing songs of defeats. But the British triumph could not last…'

Within five years the Saxons broke out of their island enclave. And new waves of immigrants arrived. In Wuffa's village the scops still sang of the great crossings from the drowning farms of the old country, tales told by grandfathers of grandfathers, just at the edge of memory. These were not bands of mercenaries; this was a people on the move.