'I broke K-15,' she said, and tilted the frying pan to get the butter over the eggs.

'Oh, Jesus,' I said, 'and you were trying to impress me by walking like a duck.'

'Thought I'd kind of steal up on you.'

K-15 was a hands-on but much-used Soviet code that the people in Codes and Cyphers at the Bureau had been trying to break for three years. I knew it had been done but I'd thought it was in London.

'Another egg?' Jane asked.

'If you can spare one.'

'No problem,' she said. 'Blackmarket.'

I didn't know when I was going to eat again. There'd been two signals from Control earlier this morning but Zymyanin still hadn't made contact. It was just gone eight, and the clothing shop wouldn't open until nine. 'Even if then,' Jane had said. 'We might have to bash at the back door.'

'You worked on it at the embassy here?' I asked her. On K-15.

'Yes. I'd be an infant prodigy in maths, if I were an infant. When I was six I used to finish Dad's crossword puzzles for him when he was at the office, made him furious. And they were in The Times.'

At the scrubbed pinewood table she said, 'Ketchup? I also created Mystere.' she watched me for my reaction.

'Did you, now.'

Mystere was also a hands-on code, non-computerized, and C and C had brought in a man from the Foreign Office to try breaking it. He hadn't managed it so far but when he did we'd destroy it, because if he could break it so could the Soviets, or someone else.