‘Yes, that’s what Geoffrey says. In time the spies of Islam will acquire the secrets of the engines. And what’s more, Islam and Christianity have no means of achieving peace with each other: history shows that, says Geoffrey. So the war will be unending, the destruction on both sides will be multiplied - the use of the engines won’t lead to victory but to catastrophe. From London to Baghdad, Geoffrey predicts, not a stone will be left standing. The only victors will be the warlords - whether fighting in the name of Christ or Muhammad it won’t matter.

‘And like all warlords, like the Mongols, they will need to feed their armies on further expansion. When the destruction of their homelands is complete they will turn their attentions outside Europe, south to Africa - and east into Asia. There will be more carnage. But China, immense, populous and ancient, will survive, as it survived the Mongols.’

‘I can believe it,’ Abdul said. ‘How many warriors could England muster? A few thousand? It’s said that the Chinese emperors command an army of a million men.’ He read, ‘“The Dragon stirs from his eastern throne, / Walks west.” I think I understand.’

Harry nodded. ‘Geoffrey says this means that the Chinese will pursue the broken European armies back across the continent, all the way to France, perhaps, and even England. The last remnants of Christianity and Islam alike will become vassals of the Dragon Throne.’

‘And when they have taken Europe the Chinese will face the Ocean Sea themselves.’ Abdul sat forward, fascinated. ‘I sailed with the Chinese, under their great eunuch admirals. Will they take their turn to explore the Ocean Sea?’

‘No,’ said Harry firmly. ‘Not according to the prophecy. Rather, the dangers of the Ocean Sea will come to haunt them . . .’

Even if the Dove did not sail west, other Europeans would surely try the journey, fragile ships from Portugal and Spain and England probing ever deeper beyond the curved horizon. Others, then, would fall on the shores of the western countries - not the empires of Asia, but lands unknown to Europe, said Geoffrey.

These more tentative explorations would benefit the strange empires of the west more than the Europeans. The Dove would have conquered - or at least he would have set an example of conquest and colonisation, as opposed to reasonably peaceful contact and trade. These more timid explorers would be overwhelmed. The strange oceanic kings would indulge in trade, but in time they would acquire the newcomers’ weapons and ships, take them apart, learn to make their own. They would suffer from plagues brought from Europe, but not in great numbers, and the generations to come would acquire immunity.

And a western empire, ruled by the ‘plague-hardened’ people of a ‘Feathered Serpent’, would learn of the rich lands across the Ocean Sea.