Tullio growled, ‘My cock is an imposing statement, but that won’t stretch from sea to sea, and neither will this Wall. Look, friend, let me put you out of your misery.’ He took a notebook, a fat block of wood, and shook it out into a strip of leaves hinged at their edges. He dipped a pen in ink and briskly began to scribble numbers. ‘Seventy-one miles, you say? Ten feet by fifteen? If there are, um, so many feet to the mile ... The point is, friend, I’ve worked with legionaries. I know how much stone or earth a man can shift in a day ...’ He came to a result; he tapped the wood leaf with his pen. ‘To haul all that stone from the quarries to the Wall line will add up to about twenty million legionary work-days. We’ll have fifteen thousand legionaries at most, and each man can manage perhaps two hundred days per year - less this year, as it’s June already. And if you divide one number by the other - yes, here we are - you’ll find it is going to take you over six years to build this Wall. Not three!’

‘But—’

‘No buts. Look at the numbers!’ Tullio threw his notebook at the architect. ‘Oh, it’s always possible to shave off a bit. Use only local stone. Push the legionaries that bit harder. Maybe make some use of local labour or slaves, but if they’re untrained they won’t be useful for much. But none of that will make any real difference. No, I’m saying you simply can’t do it, friend.’

Old Xander seemed about to burst into tears.

Severa glared at Tullio. ‘I don’t know why we’re even having this debate. The command for this Wall comes from the Emperor Hadrian himself.’

Tullio sat back and folded his massive arms. ‘I don’t care whether he’s the Emperor of the Romans or the King of the Bog People. You can’t build a six-year Wall in three years, love.’

Severa’s fury was cold. ‘Don’t you call me “love”, you fur-backed—’

‘Severa!’ Karus snapped.

Annius was studying the model. ‘Tell you what. Why not build it in turf? Just as good at keeping out the hairy lads from the north, and be done in less than half the time.’

‘Turf? Turf?’ Severa said menacingly. ‘Why, you insolent fool, if I had a clod of turf in my hand right now, I would gladly shove it down your throat—’

Brigonius touched her arm. ‘Wait,’ he whispered. ‘I’m a quarryman. I deal with fellows like this all the time. It’s all a game. Just give us some time.’

Karus stood hastily. ‘Quite right. Let’s sleep on it, shall we?’ He stood massively over Severa until she allowed herself to be escorted from the room. Then he sat down, blowing out his jowled cheeks with relief.