‘But she’s achieved her objective,’ I said. ‘A cipher is a tool, and if you can’t break it, then it has been successful. No matter how you look at it, you have no right to sneer at her.’

‘Clearly we are going to have to be just as devious as she is,’ she replied.

I asked her what kind of thing she had in mind, and she wanted me to write to Anderov and find out more about Sivincy. I knew that Anderov was very sensitive and careful, so it would not be at all easy to get anything out of him. That was why I still had not sent the letter. But in the current impasse we had no other way to learn about Sivincy, so it seemed that I would have to give this a go.

That evening, as instructed by Huang Yiyi, I wrote a letter to Anderov.

The contents of the letter seemed entirely innocuous, but I thought very carefully about my choice of words. I can’t remember exactly what I wrote, just that since coming back I had been very busy organizing Xiaoyu’s funeral, and that was why I had not had time to write to him, and that I hoped he would forgive me. I also told him that I had recently started work in a new work unit, a code school, and that now I would be teaching other people everything I had learnt from him. Apart from teaching the students encoding, I was also teaching them a bit of history, mainly the history of Russian codes. As part of that I was teaching them about some famous Soviet experts. I wrote down his name, and followed it with a list of the names of other Russians, one of whom, of course, was Sivincy. I said I didn’t have enough material for my classes, and hoped that he would do his best to send me some personal information about each of them. All this was just to hide the fact that we were trying to get at Sivincy through him.

I sent the letter, but hardly dared hope that he would actually write back.

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