‘Yes. The boss is over here: Callum Walker. I’d be interested to know if he’s ever had anything to do with Russia, and who he’s in contact with in Six.’

We agreed to speak again in twenty-four hours. I looked into Vectis, using a combination of open-source research and calls to acquaintances working at some of their rivals. Beyond its oak-panelled façade, Vectis was a global company with a staff of over three hundred analysts and seventy technology specialists. As well as the Mayfair HQ and some Gloucestershire labs there was an office on Madison Avenue and one in Berlin on the south-east corner of the Zoological Garden with a dedicated cyber-monitoring station. The firm had recently acquired a leading computer forensics and data-recovery company, which meant it had its own hackers.

I knew how it worked. Data would be processed and written up by a team of analysts in the UK, some with technical backgrounds, some experts in relevant industries or regions. Finished reports could be seen by anything up to fifteen people: there were the founders, who were mostly former MI6, then an international advisory board comprised of senior figures from industry and government. Far too many former spooks for my liking. Several of the names were familiar: an ex-chief of MI6’s counterterrorism branch; another SAS man who became Six’s head of commercial liaison. Vectis’s co-founder, Fergus Chatwell, was former head of station in Germany. Its management board included two Conservative MPs, both whom had sat on the Joint Intelligence Committee.

I called the Hilton where Walker was staying, and inquired about rooms on the floor above his own. They had one which, by my estimation, should be directly above Walker’s room. I booked it, then called Stefan.

‘I need you in Astana, Kazakhstan. Bring your kit.’

‘Kazakhstan?’

‘It’s peaceful here. And everyone uses Windows 95.’

I confirmed fees for the job and he said he’d be on a flight that evening.

I was left to think about Joanna’s double life as Vanessa McDonald. The interview with Craig Bryant had stuck with me. So had the following courtship. Both Joanna and I knew that things happened on operations, through boredom or necessity or both. Neither of us pretended that made anything easy for a partner, or even excusable. Our general philosophy was that sleeping with individuals while under cover was bad form unless really necessary.

She’d interviewed him. Footage showed a keen, optimistic technocrat. Her reports for Vectis suggested a womaniser with a drink problem. They’d had a meal at Le Dessert near Bayterek, drinks a couple of times at somewhere called Restobar, even gone to the cinema.

Then came Bryant’s repeated calls and messages:

Drink? I’ll be at the usual.

I hope I haven’t done something to upset you.

You okay? Let me know you’re okay.