Knox and Williams had used to joke that together they made the perfect agent. Knox was the brains—cautious, methodical, always questioning every angle of attack—and Williams was the brawn. He’d had an unquenchable thirst for adventure. He’d been the one who had jumped at the chance to train with the navy divers, and who had learned to fly at Shoreham Airport, a small airfield outside Brighton. He’d spent long summer evenings spiralling and diving over the town and sea while Knox watched anxiously from the ground, waiting for him to make it safely back down to the flat stretch of grass the airport called a runway.

‘Airliners are a bit different to those balsa-wood boxes you used to love so much.’

‘I don’t know,’ Williams said. ‘It sounds like the thing that’s really different these days is you.’

‘Oh, I’m the same old me,’ Knox replied.

Silence fell between them again as the A road got quieter and the countryside they passed through greener. They were getting closer to the Kent Downs, and the rolling hills that stretched out ahead of them were starting to colour with early spring flowers.

‘I just realised I have no idea where you live,’ Williams said after ten minutes.

‘I’ve got a flat in Soho,’ Knox said. ‘I told you, same old me. But I’m hardly there these days.’

‘Spending all your time above the clouds?’

‘And at Rabley Heath.’

Williams’s eyes widened at the mention of his ancestral home.

‘Someone needed to take care of the place,’ Knox said. ‘So I’ve been squatting in the gatehouse. I hope you don’t mind.’

‘No, no, of course not,’ Williams stuttered. ‘I’d completely forgotten about the old manor. At least I think I had. It’s good that you’re looking after it. Someone ought to.’ He looked away for a moment before turning back to Knox. ‘I’d like to see it again, sometime.’

‘We can,’ Knox said. ‘As soon as this is all over.’

He watched Williams’s brow furrow and gaze fall to his lap. He realised he’d let their reminisces stretch too far into the past. He needed to change the subject to something that might help jog Williams’s memories without depressing him.

‘Do you remember Belfast?’ he asked.

Williams’s head snapped back up, his mouth in a wide grin. ‘Remember it? I think I still have the hangover.’

Belfast had been a rite of passage for junior MI5 agents for decades, and Knox and Williams had served there for a few months in the late forties, shortly after their recruitment into the Service. Still reeling from the war, the government hadn’t wanted to fight any more battles the country couldn’t afford, and had grown increasingly terrified of the prospect of someone using violence to finally solve the Northern Ireland question one way or the other.