They entered the city through the west gate. It was a big double archway that had been almost blocked up by chunks of stone, so that only one person could pass at a time. A soldier in very worn armour stood here collecting more tolls, this time on behalf of the curia, the town council.

Isolde was glad to enter the town, just to get away from the desolate and depopulated British landscape. But this was not Rome. The town within its walls was a bowl of rubble, a shattered townscape of derelict houses, weed-choked gardens and silted-up ditches. The baths were shut down, the theatre was a rubble-filled rubbish tip, and even the main road was ankle-deep in filth. There were none of the public buildings she would have expected in a town this size, or if they existed they were being used for something else. There were some grand houses here, but many of them were abandoned, and as they walked by Isolde saw cooking-fires set up on tessellated floors.

Damon said that in the darkest days of barbarian incursions and banditry, the army had moved its weapons workshops and depots and stock pens within the protection of the town walls. So the town had become a fortress once more, as it had been centuries ago at the beginning of its life. Now the Roman army had gone away, of course, but Saxons and other mercenaries still used the infrastructure it had left behind.

Amid the roofless shells, heaps of building rubble and lakes of sewage, there were functioning offices, however, where the town council or the provincial government still collected taxes, organised work levies and administered justice. And Camulodunum seemed to be full of churches, small but solidly built of reused stone and tile, rising out of the general rubbish like mushrooms from compost. ‘There are more churches than people,’ Nennius joked wistfully.

Damon picked his way along the rubbish-strewn road quite cheerfully. All this was normal to him. To Isolde and Nennius, though, the whole place stank like the vast garbage heap it was. And there were so few people that Isolde felt like a child creeping through a huge house abandoned by adults.

The bishop’s palace was one of the grander buildings. It was a townhouse about thirty years old, built in something like a classical style, with separate blocks set out around an atrium. Isolde learned it had once been owned by a diocesan tax official.

Bishop Ambrosius himself was here to greet them. With receding silver hair, richly dressed in a ground-length purple robe, he was about Nennius’s age, but he looked as if he could still throw a healthy punch. When he took her hands Isolde felt reassured for the first time since she and Nennius had left Rome.