Saladin was disturbed by this bloody narrative. He had thought of England as a place of Christian peace and security - like a vast church, perhaps. But England was nothing like that. Wars had been fought out here and invasions mounted, and people were forced to huddle behind the walls of towns like fortresses. And it was all so insular. Did the posturing princes of this little country have no idea of the threat posed by the Muslims, who had taken three-quarters of Christendom - and, worse, the Mongols, who by all accounts had conquered three-quarters of the whole world?

At the very heart of Colchester was a Norman castle, a little like the brooding pile in London but even more imposing. ‘The most massive keep in the whole country,’ Thomas said. The castle’s thick walls were heaped over a tremendous slab of concrete sunk into the sandy ground. Local legends had it that the slab had been the foundation of a great Roman temple. ‘Think of the size it must have been! Who would build such a monument in this dismal place? But some of the locals claim that before the Romans came this town was already the capital of the whole of Britain.’ Thomas shook his head. ‘I suppose we would all like to believe we are descended from kings.’

Yet, Saladin thought, that mighty concrete slab had been poured into the ground by somebody, for some purpose. But his brief flicker of historical curiosity quickly died.

Thomas led them to his priory, a few miles outside the walls of the city. It was a modest house of a few dozen monks, supported by the sale of wool and tithes paid by the inhabitants of a small village, through which they had to walk. The houses were long, leading back from a central trampled track. It seemed that a family lived in each house along with their animals: there were no barns or sheep-pens or pig-sties, only the houses, for people and animals to share. The smoky air stank of the dung used to fuel the fires. A litter of grimy children followed the travellers, wide-eyed.

Compared to the aridity of the Outremer, the land here in the heart of England was green, and so wet that wherever you saw a ditch you had to assume it was for drainage, not irrigation. But the villagers scraping away at their long, skinny fields looked half-starved and exhausted. And there seemed to be an awful lot of children here, a lot of mouths to feed; no wonder the villagers had to work so hard.