Knox decided to go back to Sweden. He flew to Stockholm, and spent a couple of days exploring the city and, inevitably, having some conversations with the Swedish security service. Their representative was a very tall, straight-talking man called Alve. Knox liked him immediately.

Alve filled in some of the details about Valera’s long, hard journey from Russia to Sweden, and Knox reassured Alve that sending illicit extraction teams into foreign capitals was not standard MI5 procedure. Learning more about Valera and her life gave Knox a greater appreciation for what she’d gone through, but he still wasn’t sure he’d ever forgive her for shooting him.

He then spent another week driving a rented Saab along the southern Swedish coast, on Alve’s recommendation. A fortnight after he’d returned to London several crates of teak furniture and Scandinavian art arrived at Kemp House.

Since the new year, most of Knox’s time had been taken up with monitoring the Committee of 100, the direct-action wing of the Campaign for Nuclear Disarmament. It had spent 1961 committing increasingly bold acts of civil disobedience, staging protests across London and at military bases all over the country. But the wheels were now starting to come off, and Knox was in charge of making sure they didn’t cause any damage when they did. MI5 had braced itself for a long summer of watching the Committee implode. But, after the CND’s annual Easter march, things had gone quiet. It turned out the Committee and the CND were both almost broke.

Knox’s last few months had been fairly subdued, consisting mainly of reviewing reports, catching up on training, and waiting for the events of the previous summer to come back and haunt him.

It had taken Finney two weeks to arrange for Bennett to be accepted into CIA field agent training and be sent back to America. Given the events around the OECD conference he couldn’t deny that she was talented, but she also needed some of her rougher edges smoothed, and ideally somewhere far away from him. He didn’t enjoy being accused of treason by his junior staff.

‘Are you sure it’s what you want?’ Knox had asked when she told him. ‘You’re still more than welcome at Leconfield House.’

‘I will miss this city,’ she’d replied. ‘But I hate to walk away from a challenge. Especially one I made for myself,’ she added with a smirk.

On her last day in London, Knox had taken her to Bar Italia. After they’d both finished their espressos, she pulled two photographs out of her bag and slid them over the counter.

‘Who are we after now?’ he asked.

‘A going-away present,’ she replied, smiling.

‘I think I’m supposed to get you one, not the other way round.’