Five years after the divorce, my ex-husband chose the seat next to mine in first class — there were four empty ones

There are about sixty. They run from the October of 2020 to the February of 2021. They are to a number saved only as P.

And they say things like: can't talk here. And: same place, nine. And: don't put anything in writing. And, on one occasion, at twenty past eleven at night: I'll come to you.

Read cold, on a bedside table, by a man who is tired and looking for something — they are exactly what he decided they were.

P is Dr Priyanka Ramnath.

She is forty-five, she was at university with me, and in 2020 she was a senior engineer at an independent testing body.

And here is what we were doing.

In the September of 2020 I found a defect.

Aldritch Systems makes structural monitoring — sensor arrays that go onto bridges, car parks, older commercial buildings, and report on movement and load.

The whole value of it is that it tells you when something is going wrong before a person can see it.