But she suspected that Ari suspected she had a deeper agenda. After all, two years on, Ari was still one of only a handful of Brikanti to know that she came from a different historical background – and, she thought, one of even fewer who actually believed the reality of it all. But, suspicious as he was, he had allowed her to go ahead with these side projects. Penny wondered if Beth Eden Jones had had something to do with that – maybe she’d used a little pillow talk. And Beth was, after all, carrying Ari’s baby …

And here he was now, sitting at the back of her class like some school inspector, a half-smile playing on his lips as she lectured these children about the possibility of counterfactuals. Well, he was right to be suspicious. Of course she had an agenda. Of course she was playing a long game. Saint Jonbar, indeed!

She focused on her students, on the Mongols.

‘So everything hung in the balance. All history might have been changed. But that did not happen. Does anybody know—’

There were some shout-outs, but a forest of hands were raised more politely, as she’d patiently taught them. This was a warrior culture after all, they did have Vikings in their ancestry; at the beginning Marie had said she was lucky the students didn’t try to attract her attention by throwing axes at her head.

She picked out a student at random. ‘Yes, Freydis?’

The girl stood up. ‘The great Roman Emperor Constantius XI sent an embassy to the Xin empress, and persuaded her to join forces and attack the Mongols.’ She sat down just as sharply.

‘Yes. That’s essentially right. Except that it was actually the other way around …’ That history-changing bit of state craft, an alliance between bitter rivals that had probably saved two empires, had been initiated by strategic geniuses in the Xin court. But Roman historians, propagandists all, had from that moment given the credit to Constantius. The Brikanti, for all their stated rivalry with Rome, were in some ways in awe of the mighty Empire that had once come so close to destroying them, and had allowed their own view of history to be dazzled by such lies.

‘But the point is that because the two rulers were able to put aside their own suspicion and ambition, the Mongols were defeated. Without that everything would have been different. That’s what I want you to take away from this lesson today … Yes, Freydis.’

The girl stood again. ‘Maybe it’s like when Queen Kartimandia told the Caesar to attack Germania and not Pritanike. If she hadn’t done that …’

Her face shone with the excitement of discovery, of finding a new idea, a whole new way of thinking. Penny was no natural teacher, and at seventy-one years old she was finding the daily classroom routine a grind. But at such moments, when a spark was lit in a young imagination, she could see why people would teach.

But Freydis’s contribution hadn’t gone down well with her classmates; there was laughter and catcalls. ‘Yes, Freydis, and you’d be speaking Latin now!’

‘So would you,’ Freydis snapped back.

‘All right, all right.’ Penny stood, holding up her hands. ‘That’s enough for now. Time to break for lunch—’

The room turned into a near riot as the students grabbed their stuff and jumped up from their benches. Marie Golvin yelled with parade-ground lungs, ‘Back here in one hour for relativistic navigation!’

Ari Guthfrithson, with quiet dignity, let the tide of youngsters wash past him. Then, when the room was empty, he walked towards Penny, clapping his hands. ‘Skilfully done. And all delivered in correct Brikanti, halting and with an exotic accent as it is. I do continue to wonder why, you know, you pepper their brains with such ideas, the fragility of history. It wasn’t the stated purpose of the Academy after all.’

Before Penny had to answer Marie Golvin, who had been collecting up scrolls and paper scraps from around the room, joined them. ‘Will you have lunch with us, druidh? Nothing exciting, I’m afraid.’

‘I’d be honoured. And that was a neat deflection, by the way, Lieutenant Golvin.’ It had taken him some time to memorise the term for Golvin’s ISF rank. ‘Well, shall we walk?’

CHAPTER 16

The Academy of Saint Jonbar had been established on the edge of Eboraki, away from the crowded ancient core of the city, in what Penny might have called an outer suburb. The refectory where they would eat, though attached to the Academy, was a short walk out of the campus and towards town.

The main schoolhouse was one of a cluster of new buildings, all roundhouses, which included a gymnasium, a library, an arts centre, a small clinic, a workshop for pottery, metalwork and other crafts, and a Christian chapel. The buildings were arranged in neat rows, like the city itself aligned not north-south but on a north-east to south-west axis, the direction of the solstice sunrise and sunset, following Brikanti tradition. There was a grassy playing field, and a kind of parade ground where some of the students, cadets in the armed forces of the Brikanti, could practise marching, and wage mock battles with swords and even blank-loaded firearms. But all this was set in an oak grove, one of a number studded around the city, the tree a symbol of ancient druidh wisdom.

Penny and Marie had together designed this complex, with advice from Ari and other locals, and all paid for by money Ari had managed to extract from Navy contingency funds – the military-college aspect had been part of the price they’d had to pay for that. To Penny, even now, it looked like a museum piece, like a reconstruction of some Iron Age village rather than a brand new, living, breathing facility for young people.

Of course those few students who went on to become full druidh wouldn’t be so young when they finished. Ari, for instance, had gone through a few years of general education, including history, geography and philosophy, followed by twenty years of specialist study in law, politics, and mathematics and astronomy. Nowadays this was a literate culture, but Ari had told Penny that the old pre-literacy tradition of memory training, the recall of long passages, was still used to develop the mind. Mathematics was particularly strong here. Penny herself had supervised classes of young children learning to reproduce the outlines of mistletoe seeds using the arcs of circles, carefully drawn with compasses and pens. It was easy to see, given such beginnings, how the Brikanti grew up to be such fine astronomers and interstellar navigators: from the geometry of a mistletoe seed to the trajectory of a starship.

The principal town of Eboraki was evidently a more ancient community than the Roman-planted towns in Gaul and Germania, and the older traditions of Celtic architecture and town planning lingered on, not obliterated by later Roman developments as in Penny’s timeline. A grid pattern of roads of gravel and crushed rock separated houses of wattle and daub with thatched roofs, all surrounded by a monumental wall, outside which lay cemeteries and funeral pyres. The higher ground in the centre of the city – in Penny’s world dominated by a cathedral that had stood on the site of a demolished principia, headquarters of a Roman legion – did bear the remains of a two-thousand-year-old fort, but here it had been a Brikanti-built bastion, a relic of the days when continental invasions had been feared and experienced. This Britain, for better or worse, had never been severed from its own past by a Roman sword.

Studying this new history with her students, Penny had come to understand how much harm the Brikanti and their continental cousins, who Penny had grown up knowing as the Celts, had suffered at the hands of the Romans. Once the Celtic nations had prospered across Europe from Britain to the Danube, but the Romans’ empire-building expansion had driven them back. Though Britain, in this history, had remained independent of Rome, elsewhere the Celts had been crushed. When Caesar had invaded Gaul, a prosperous, settled and literate country, of a population of eight million he had slaughtered one million and enslaved another million. One detail particularly remembered by Brikanti historians was that Caesar had severed the hands of rebels, so they could not gather their harvest. This history was not well known in Penny’s timeline. Here, it had never been forgotten.