I walked past the church, past a low-ceilinged pub, to the point at which I’d usually leave her, at which she said we had to part. The edge of the village. She said they monitored the village.

I headed for her house.

Joanna didn’t explicitly talk about Shefford when we were together. We both wanted to escape thoughts of work anyway. So we just walked, often in silence, amused by the brazen beauty of the countryside.

I don’t know what she was doing, but she implied that fieldwork – the basic craft of recruiting human agents in a hostile environment – would become even more irrelevant in the future. That triggered our argument the last time I saw her. I was mentally preparing myself for a return to the Middle East. I wasn’t in the mood for someone suggesting that I was wasting my time. She presented her own removal from overseas operations as a conscious choice, which was clearly designed to get a rise out of me. And, I thought at the time, reflected personal bitterness. She had been a better field officer than me. A group of us had been selected to spend two weeks in Brunei learning advanced weapons skills, some abseiling and parachuting. She was in her element, to the extent that there had been talk of moving her to the Special Reconnaissance Service, which they were in the process of setting up, a dedicated sub-unit of the SAS designed for the new era of cyberwarfare. Unlike the SAS and SBS, it took women. Like them it was comprised of an elite with the mental and physical ability to work in small, independent teams under life-threatening pressure. She said she wasn’t one for painting her face and lying in puddles.

One fragment of that last, needling semi-drunken conversation had stayed with me more than the rest.

‘They have software that can tell you how long a relationship will last,’ she said.

‘Based on what data?’

‘Everything: geographical movement, sleep patterns, conversational rhythms, vocabulary, choices of entertainment options.’

‘What does that allow you to do? Marriage guidance?’

‘It means, theoretically, if you wanted a relationship to end, you could run the program backwards and see what steps would engineer that outcome.’

That was a somewhat loaded anecdote to share, I thought. I wondered if the ruthlessness was meant to impress me. We were on the third bottle. She looked strikingly beautiful, her eyes large and liquid, as they became when drunk, and which was sometimes a warning sign. Head held high on her long, pale neck, hair escaping its knot to hang around her face, a wildness in her echoing the woodland around us.

‘Is that what you’re doing? Breaking hearts? People seem able to ruin their own relationships.’

‘It’s knowledge. It’s intelligence.’