‘And so you came across the ocean. The sea rises, and we petty humans must flee. Before such forces, the coming and going of empires seems trivial - don’t you think? But there may be deeper patterns yet.’ Ambrosias leaned close to the two young men, peering into their faces. ‘I once met an old man, a poor Briton fleeing west from the Angles, who told me of an ancient legend - it must date back thousands of years if it is true at all - that once you could walk across the ocean, or rather the floor of what is now the ocean. But the sea rose up. Sometimes, if you dig in the exposed sands on the coast you will find reindeer bones, even a stone tool or two. Do you think that we are all one, we people of the lands surrounding the ocean, that in a sense you are not migrants, you have simply come home?’

The idea was astounding to Wuffa. ‘But how you could ever tell if that was true?’

Ammanius grunted grudging approval. ‘An intellectual answer. I could make a scholar of you, wolf-boy, given time.’

Ulf, always more earthy than Wuffa, was uninterested. ‘We have no legends of drowned lands. My people are warriors.’

‘Ah, warriors,’ said Ambrosias. ‘The world is never short of warriors! When I was an infant my father presented me to the greatest warrior of all. Have you young blades ever heard of Artorius?’

They had not. Ambrosias seemed shocked.

Ammanius told them that as the German immigrants expanded from their coastal footholds and conflict spread across the island, the British found a general in Artorius, who had the authority to work across the boundaries of the province-states and organise significant resistance. He won a string of victories. ‘Artorius’ may have been a nickname, meaning ‘the Bear man’, perhaps a reference to his size. He was said to be the nephew of one of the last Roman commanders to have stayed at his post in Britain.

‘All this was a century after the Roman severance,’ Ammanius said. ‘Artorius won peace for a generation. But all he really secured for his people was time.’

Wuffa asked, ‘So why would this Artorius come here?’

‘He retired here after a last battle,’ Ambrosias said. ‘Already an old man he was gravely wounded - worn down by the treachery and cowardice of his own men as much as the enemy’s efforts. He died, here at Banna - on the Wall, the greatest monument of the empire to whose memory he devoted his life.’ He was misty-eyed now. ‘In another age they would have built him an arch here to rival any in Rome! And I, a child, was presented to him. He ruffled my hair! Here.’ He knelt stiffly, presenting his bowed head to Wuffa. ‘Touch my scalp. Go on!’