Pol said gently: "I came to talk to you here because it is a good place. Better than a cafe or your hotel. I was not seen coming here, and if you would care to move your chair back we should be completely concealed, in this light."

I said: "You're mistaking me for someone else. Don't oblige me to call the usher and lodge a complaint."

He said: "Your attitude is understandable, so I won't cavil."

I moved my chair back and sat closer to him.

"All right," I said.

` Windsor ' was the presently operating code-word, given as a name, when approaching a contact. The C-group had been in operation since the first of this month, giving us `care,' ` call ' and `cavil.' I would have cleared him provisionally on 'cafe' alone, because he knew three things about me: my name was Quiller, my box number was 7, and this was my last night in Berlin. But I had thrown him ` call ' to get ` cavil' simply in the hope that he wasn't a contact at all, but someone who had wandered into the wrong box and used the word 'care' by chance.

I didn't want any more contacts, any more work. Six months in this field had left me sickened and I wanted England more than I had ever wanted her before.

It was no go. This was a contact.

Uncivilly I told him to explain how he had known which box I was in.

He said: "I followed you here."

"You didn't." I knew when I was being followed.

"Correct," he said.

So it had been a test for me: he had wanted to know if people could follow me about without my realising it. I resented the trap.

"We knew that you had reserved this box," he said.