Mackie read:

Ah child! Bound in time's tapestry, and yet you are born free Come, let me sing to you of what there is and what will be, Of all men and all gods, and of the mighty emperors three…

'We don't know how much was lost, and how much has been garbled in the repeated transcriptions. We don't even know the purpose of the deflection, if it was a deflection. Geoffrey speculated it had something to do with the Emperor Constantine.'

'Constantine? He was centuries later. What's he got to do with the price of fish?' He glanced down the lines again.

Remember this: We hold these truths self-evident to be -

I say to you that all men are created equal, free

Rights inalienable assured by the Maker's attribute

Endowed with Life and Liberty and Happiness' pursuit.

O child! thou tapestried in time, strike home! Strike at the root!

Hmm. I'm blowed if that doesn't sound familiar.'

She smiled. 'An American would recognise the reference straight away.'

'Ah. Let me see if I can remember. "We hold these truths to be self-evident, that all men are created equal, that they are endowed by their Creator with certain unalienable Rights, that among these are Life, Liberty and the pursuit of Happiness. The Declaration of Independence.'

'Right-'

'Good Lord.' The implications seemed to hit him then, and he sat silently for a heartbeat. 'I think I'm going to have something eke to keep me awake at night, apart from Godel's banishment of time… So a modern figure sent this back to pre-Roman Britain? Why? To establish democratic values back in the Iron Age?'

'Maybe. But, Tom, the important question is not why but who.'

'Ben's friend Rory O'Malley, perhaps.'

'Yes. O'Malley was an idealistic Irishman who was a great admirer of the US. And he was a lapsed Catholic. He had grown up amid a lot of religious sectarian tension. In the US, before he went to Spain, where he met Ben, he wrote a whole series of articles attacking the Church's oppressive nature, and the evils done in the name of organised religion.'

'Hmm. Wasn't Constantine responsible for the establishment of Christianity as the Roman state religion?'

'He was indeed. You can see there's a tenuous case to be made that the Nectovelin document was authored by O'Malley, in order to deflect Constantine's establishment of the Church. He even sent it back to 4BC, the year Christ was born, to establish the link with Christianity.'

'But O'Malley is dead. And if there was ever a record of any material he tried to transmit to the past, that's lost too. We've had agents go over everything O'Malley left behind at Princeton. Like all Nazis, Julia Fiveash is nothing if not thorough…' Mackie snapped his fingers. 'But then there's Kamen. If Rory used him he ought to know what was sent.'

'Yes,' Mary said. 'Precisely. Ben knew what had been crammed into his head. And it was following up that that led him to Geoffrey Cotesford's research.'

'Well, well. So we've another reason to get hold of this young man, if we can.'

'I do wish we had a more complete copy of the Prophecy,' Mary said. 'There could be more internal evidence. For instance, an acrostic.'

'A what?'

'A feature that appealed to classical and medieval scholars. You take the first letter of each line, or the last maybe, and put them together to make a new word or phrase. But this document isn't nearly complete enough to tell…'

He fingered the papers. So what else did your chum Geoffrey dig up?'

'A lot of material. I'm still exploring it. Not all of it may be relevant. But I think this is.' She produced another document, another prophecy. It was in Old English, with a modern translation. It was called the Menologium of Isolde. 'It's reasonably complete.'

Mackie read a bit.

These the Great Years /of the Comet of God

Whose awe and beauty / in the roof of the world

Lights step by step the / road to empire…

'Who was Isolde?'

'Apparently a relation of Nectovelin, generations later. The family link may be significant – an inherited susceptibility.'

'And what is a Menologium?'

'A kind of medieval calendar. According to Geoffrey this is another product of Birdoswald, this one produced some time towards the end of the Roman period, the early fifth century. You can see it is organised around the return of a comet to the skies, every seventy or eighty years. It traces through events fated to occur in these years – I've made guesses about some of them. And, it's a little tricky, but you can reconstruct the dates by adding up these "months of the Great Years. And they match to the events they describe – the Vikings sacking Lindisfarne, a terrible fire in Rome.' She paused for effect. 'The ninth verse seems to relate to the year 1066.'

He was startled, and he laughed. '1066? Harold and the Normans, and all of that? Well, you've come on an appropriate day to talk about it, haven't you? And – wait a minute – didn't a comet turn up in that year and frighten everybody to death?'

'So it did. It was Halley's comet. It returns on average every seventy-six years. But the intervals differ a bit each time.'

'Should think they would,' he muttered. 'Deflections by the planets' gravity and so forth…' He ran his finger down the text of the Menologium. 'Don't tell me. The dates of these verses map onto what the astronomers say about Halley's returns.'

'As far as I can tell. But if the text did originate in the fifth century – look, Halley's motion is well understood now, but it wasn't in 1066, or any time earlier. A fifth-century author couldn't have known these dates.'

'Well, well, well. And you think this has something to do with our German chums?'

'Look at the Epilogue.'

He glanced down and read:

Across ocean to east / and ocean to west

Men of new Rome sail / from the womb of the boar.

Empire of Aryans / blood pure from the north.

New world of the strong / a ten-thousand year rule.

'Well, bugger me sideways.'

'That crucial word "Aryan – it comes from a bit of Latin in with the Old English, "Imperium Aryanes… I'm still working on the interpretation of the rest of it, but-'

'So the suggestion this time is that some Nazi has sent this back – perhaps to deflect the events of 1066? – in order, somehow, to establish an Aryan empire, a thousand years earlier.'

'Something like that.' She didn't feel confident enough to tell him of Josef Trojan's boasting at Battle of putting right the defeat of Harold Godwineson. 'The suggestion is that the English King Harold should have made peace with the Danish invaders, and cooperated with them to drive out the Normans. If he had, all subsequent history might have been different. But he didn't take the advice, evidently.'

'Well, it's completely bonkers. But Himmler would love it, wouldn't he?' Mackie laughed, and laced his fingers behind his head and lay back in his chair. 'Funny – the second time we've come across evidence that somebody is tampering with history seems a lot less startling than the first, doesn't it? The mind can get used to anything, I suppose. Well, we're getting somewhere, aren't we, Mary? The question is what we do about it. I believe the objective is clear: we get into Richborough, we find out what these beggars are up to, disrupt it if we can – and we bring Ben Kamen out.'

Mary said, 'You keep saying "we".'

He smiled. 'You spotted that. I think I'm having a bit of a brain wave. Look here, Mary, suddenly you're a jolly useful asset. The fact is, a citizen of a neutral country has a much better chance of passing through the Winston Line, and of travelling reasonably freely once he or she is in the protectorate itself. And we do believe Kamen was held in the same camp as your son, at Richborough. So you have a reason to go to that part of the world, don't you?'