‘You think so?’ Severa said slyly. ‘Look at that.’ She pointed to a farmhouse, a complex of whitewashed tile-roofed buildings surrounded by gardens and set amid extensive fields: it was grand, even palatial. ‘You could transplant such a house as that to the Mediterranean and it wouldn’t look out of place. And what about that?’ On a river bank to the east, dimly seen in misty air, a great wheel turned slowly. ‘It is a mill,’ she said. ‘For grinding corn, using the power of flowing water where once human muscle or oxen would have done the job. You can use the wind, too, if you’re clever enough. The farmers are even breaking land on hilltops and in river valleys they previously thought not worth working. The population is rising too. I know this is true because the Romans measure such things.’

Brigonius snorted. ‘The Romans count us so they can tax us. The farmers only grow more wheat to meet the demands of the soldiers who push us around. And then they have to pay tax on the coin they earn.’

‘Yes,’ Severa said, a touch impatiently, ‘but that’s the point. You have to see all of this as a great wheel, Brigonius - like the waterwheel of the mill over there. Once the farmers grew only for themselves. Now they grow a surplus, which they take to the towns to sell. The taxes they pay on their profits are used to develop the towns and to pay the soldiers, who, hungry, must be fed by the farmers’ surplus ... Around and around it goes, a wheel driven by a river of money. And everybody benefits, everybody grows prosperous, and everybody is at peace. Why, there have probably never been more people alive in Britain than today. What’s wrong with that?’

‘But what’s the point of it all? The mill-wheel grinds flour for bread. What purpose does your money-wheel serve?’

‘Why, it grinds up people. It smashes up petty tribes like your own and bakes the fragments into an empire.’

‘It makes everybody the same,’ Brigonius said resentfully.

‘Yes! And that is the power of it.’ Severa dug into her purse and produced a coin, stamped with Hadrian’s head. ‘Look at this, Brigonius. You could travel along roads just like this one from Britain to Asia, and everywhere you could ask for your daily bread in Latin, and pay for it with this coin. A single language, a single currency, right across a continent. And Britain is part of it! Don’t be sentimental, Brigonius! Open your eyes and see the shining future - and embrace it.’

As she made this little speech she touched his hand. Her grip was strong, her flesh oddly cold. Looking at her pale eyes he saw her ambition, and he wondered uneasily just how unsentimental she would prove to be in pursuing her goals.