After a moment he went on, 'You're right; the bridge will change things. The river used to form a natural boundary. The Atrebates and Cantii roamed to the south, the Trinovantes and Catuvellauni to the north. The floodplain was no man's land.'

'We Romans were the first to deploy the corridor, making the river a highway?'

'Before we put in decent roads it was the best way to move around supplies, Marcus. The estuary is navigable way up to here – and in the early days ships were more secure than trundling goods across country. They can float up on one tide, then back on the next. After the Rebellion we made this the provincial capital and now it's a major import base.'

'New city, new formal administrative centre -'

'And new problems!' said Hilaris, with unexpected feeling.

What problems? Did he already know what we were dealing with? It seemed a cue to discuss the Briton's death.

'Verovolcus,' I admitted, 'might have been in that district close to the river because he was trying to arrange transport to Gaul.'

I made no overt link to the problems. Whatever that was about could wait.

Hilaris turned his neat head and considered me. 'You knew Verovolcus' movements? Why was he going to Gaul?'

'Exile. He was in disgrace.'

'Exile!' Some people would at once have asked me why. Ever the pedantic administrator, Hilaris demanded, 'Have you told the governor that?'

'Not yet.' I had no option now. 'Oh, I like Frontinus. I've worked with him before, Gaius, and on confidential matters too. But you're the old lag in this province. I was more likely to tell you.' I smiled, and the procurator acknowledged the compliment. 'It's a stupid story. Verovolcus killed an official. His motives were misguided, he expected royal protection – but he had misjudged Togidubnus.'

'You exposed him.' A statement, not a question. Hilaris knew how I worked. 'And you did tell the King!'