Ammanius prompted, ‘And the story of Isolde?’

It had happened nearly two centuries ago, Ambrosias said, in this very fortress. Isolde, then a young girl heavily pregnant, had been hauled all the way here from Rome by her own father, for purposes of his own. Far from home, Isolde had given birth, to the first of a line of five males that would eventually lead to Ambrosias himself.

And as she was in the pains of labour, she began to speak: to gabble in a tongue that was alien to herself and her father.

Ammanius was tentatively interested. ‘She spoke in tongues, then. It is a common miracle. Did she speak of the Christ?’

‘Oh, she mentioned Him,’ Ambrosias said. ‘But what was miraculous about it was that the tongue she spoke was German.’

Wuffa could see that that detail jarred with Ammanius’s notion of what constituted a proper Christian miracle. But it intrigued Wuffa, for to him it made it seem more likely that something remarkable had happened, that this hadn’t been a mere plague fever. What possible insanity could cause a Latin-speaking woman suddenly to spout German?

Sulpicia asked, ‘And did she speak of the future? Was it really a prophecy?’

‘Oh, yes, Nennius and the others with her recognised it as such immediately. They wrote it down, and it has been preserved by my family, in this place, ever since.’

Ammanius pressed, ‘What did she say?’

Ambrosias sighed and gulped down a little more Anglish ale. ‘Well, I’ll tell you. Tomorrow we will discuss the past and the future and similar nonsense. But for now let us talk of other things. I am starved of educated conversation, stranded here among illiterate Germans. You are tired - or if you aren’t, I am - and most of us are a little drunk on this scummy ale, I suspect.’ He eyed Ammanius when he said this, and the bishop glared back.

Ambrosias turned to Ulf and Wuffa. From the moment they had met he had seemed far more interested in the two young men than in the bishop or the girl, although there was no trace of Ammanius’s lasciviousness in him. Ambrosias asked where the two of them were from, and they tried to explain, though their lack of a common geography was a problem: to Ambrosias they were both simply barbarians from beyond the old empire.

‘And now you are here,’ Ambrosias said, ‘on the west coast of Britain, so far from home.’

‘My people came to Britain,’ Wuffa said, ‘because of the sea. So my father told me. Every year the tides came higher. The beaches and cliffs eroded away. We were forced to retreat from our farms, which became waterlogged. But there was nowhere for us to go, for the land was full.’