‘We are here, my friends, at Piroboridava, and we are alone. People don’t live up here – at least no one with any sense. And they don’t pass this way if they can help, least of all in winter. So all this garrison sees are those trees. Day after day, you look out and there they are. It’s the closest we get to company.’

‘Company?’ One of the clean-shaven Britons had spoken. The man was frowning, and appeared almost on edge. Sabinus struggled to recall the man’s outlandish name. Mobacus or Molacus? Something uncouth, he was sure.

‘Yes, my dear fellow.’ That seemed wiser than risking getting it wrong. Sabinus beamed at him and the others, resigned to the lack of interest shown by Ferox and making the most of the rest as the only audience on offer. ‘Although you may not believe it, you will grow fond of those trees. Once you have been here a month you will surely grow to love them. When you have been here two months you will start to talk to them.’

Ferox, knowing what was coming, had to force himself to keep staring out, apparently without a care in the world.

‘Talk to them?’ That was Molacus, always too quick to speak and too ready to show scorn.

‘Most certainly,’ Sabinus said, enjoying his little game. Ferox could imagine the centurion’s serious expression. ‘You will indeed talk to them – all of us do.’ He paused, drawing out the moment. ‘But it is only after you have been here three months that the trees begin to answer.’

There was an amused snort from Vindex, prompting a delighted chuckle from Sabinus, and at long last the other two joined in. The sentries were not officers, and were not involved, and like Ferox they must have heard this so many times before. It was an old joke, even by army standards, told of countless forts and outposts dotted around the empire, and sometimes it was sand dunes, mountain tops or even sheep instead of trees. He let himself smile, out of nostalgia as much as anything else, then saw the movement beyond the bridge and grinned in satisfaction. They were coming and soon he would know.

‘Riders, sir!’ Maternus shouted. ‘Two, no, three of them, leading another pair of horses.’

Ferox stood up straight and faced back towards the others.

‘Yours, sir?’ Sabinus asked.

‘Vindex?’ Ferox already knew the answer, but needed to play his part.

Vindex squinted, shading his eyes. ‘Aye,’ he said. ‘It’s Ivonercus and the other lads. Coming slow, so maybe the mare is still lame. … Could just be the ice though.’

‘Wise to be careful.’ Ferox smiled. ‘Now, my dear Sabinus, perhaps we could take a look at the ditches.’

‘The ditches, sir?’ The centurion had hoped that the new arrivals had already seen all that they wanted so that he could escort Ferox to his quarters and then return to his own.

‘The ditches,’ Ferox repeated. ‘I had better see all the defences of my new post. And perhaps we will stroll down to the bridge as well.’