Wuffa and Ulf spent some days escorting Ammanius to other south-east ports, where the bishop had to supervise more bands of refugees fleeing to the continent. Many of the ports had massive old Roman fortifications like Reptacaestir’s. The only one Wuffa had heard of was Pefensae, which the bishop called Anderida. Here, after the Romans, a British town had grown up within the walls, but a century ago the Saxons had landed here and slaughtered every last Briton, a bold strike of which the scops still sang.

With Ammanius’s obligations fulfilled, the six of them set off for the far north, in search of the legend of Isolde.

Their journey mostly followed the roads left behind by the Romans, some of which were well maintained, some not. Ulf and Wuffa travelled by horseback, while the bishop, Sulpicia and the novices rode in a sturdy Saxon cart. Britain was full of petty kingdoms, but Ammanius was able to transfer them from the protection of one polity to the next through letters he carried from his archbishop - and, Wuffa thought, by his own sheer force of personality.

By night they stayed in old Roman towns, or in forts on top of hills, or in villas in the countryside. Ringed by hastily built walls the towns were more like shabby fortresses, where amid thatched houses of mud and straw a few mighty stone structures loomed. In the Roman-British domains the towns were protection in bad times, markets in good times, and places where kings or other petty rulers collected their taxes.

The forts on the hills were more interesting to Wuffa, because they were so different from anything he had seen before. They were fortified not by stone walls like the towns but by earthen ramparts and wooden palisades. Ammanius, aware of Wuffa’s growing curiosity, told him these forts had brooded on their hills long before the Caesars ever came. ‘And later the British drifted back to the fortresses of their ancestors. It was as if the Romans had never been here at all ...’

Ammanius preferred to stay in the villas. Grand old farmhouses, once owned by rich Roman British, they had been either abandoned when the Roman system broke down, or occupied as much-reduced farms. And later, as Britain’s Christianity spread, they became monasteries.

Here, surrounded by the calm toil of monks, Bishop Ammanius evidently felt at ease. And as he relaxed he drank. Holy man he might be, but Ammanius was fond of his wine.

And the drunker he got, the more fascinated he seemed by Ulf and Wuffa. Ammanius spoke more often to Wuffa. He said he saw the ‘empty minds of two pagan boys’ as vessels to be filled up with his God’s truth. But when the big Norse moved the bishop’s stare always followed, as if Ulf were some fascinating animal.