Orm shrugged. ‘Savages. Ugly and brutish. They sail in boats sewn together from skin, and their women stink of fish.’

The Vikings killed eight of the skraelings, but one escaped. Later, more came boiling out of the forest, seeking vengeance.

‘That was why the settlement was abandoned. Just too many skraelings. But there are many who still regard Vinland as their home.’

‘And some day the Vinlanders will return,’ Godgifu said. ‘To reclaim their land from the skraelings.’

‘Perhaps.’

‘Oh, they will,’ Sihtric said. ‘The prophecy demands it. Now we come to the crux of the matter. Orm, when exactly did this Bjarni—’

‘Bjami Herjolffson.’

‘When did he lose his way and find Vinland?’

The date by the Christian calendar turned out to be hard to establish. Orm, like most people, remembered the years not by numbers but by great events: wars, the passing of kings, the coming of plagues or floods - or strange lights in the sky, like the comet of the prophecy. At last they established that the year of Bjarni’s voyage had been during the long reign of Edward’s father Aethelred, a time when the Danes were ravaging Britain - and that year, a murrain, a cattle disease, had afflicted England.

Sihtric had another document in his bag, a closely-written little book, a copy of a chronicle of the years that had been kept by English monks since the time of Alfred. It turned out that there was only one year in Aethelred’s reign noted for a murrain: the year 986 AD.

‘I knew it.’

‘I don’t see what you’re getting at,’ Orm admitted. ‘There is no “986” in your prophecy.’

‘Ah, but there is - embedded in its puzzles. Look again at the seventh stanza.’ He fumbled with his scroll, unrolling it. ‘“The dragon flies west ... Know a new world born.” What else can that mean, but the discovery of Vinland by you Vikings? And the stanza says more. “Less thirty-six months ... Know a Great Year dies ...” My Moorish colleague has dated the end of the seventh Great Year, the seventh cycle of the comet, as September, AD 989. He does this by adding up the given months and dividing by twelve, so that—’

‘Yes, yes.’

‘And the “less thirty-six months” gives a date of three years before the Great Year’s end. So the prophecy predicts Bjarni’s discovery - in the year AD 986.’ And he slapped the cover of his chronicle in triumph. ‘I knew it.’

Godgifu seemed shocked; it seemed that the priest hadn’t shared this secret even with his sister. She asked uncertainly, ‘But what does this mean?’

The priest rolled up his parchment. ‘I hold in my hand the power to shape history. That’s what it means.’

At last they were passed by the guard at the door, and made their way inside the palace. Sihtric led them through the crush of jostling English nobility towards the King’s bedchamber.