The first event was the junior relay race. There was a lot of shouting, shoving and jumping up and down in mock excitement. Fiona put her head close to mine and said, 'I was thinking about Giles Trent. Was he expecting his sister to call, that night he took the overdose?'

'They both say no, but maybe they are both lying.'

'Why would they lie?'

'Him because he's too public-school macho to admit that he'd pull a stunt like that.'

'Why would the sister lie?'

'If she admitted that Trent was expecting her, she'd have to start wondering whether that "cry for help" was her brother's way of telling her to lay off.'

'A drastic way of telling her, wasn't it? Couldn't he tell her over a cup of tea?'

'His sister is a formidable lady. She is not the sort of woman who would admit that her brother need sell his soul to provide her with a man. She would have grunted and shrugged and ignored whatever he said.'

'But by that time serious pressure was coming from the Department and from his Russian contact. Did he think a suicide attempt would make the Russians lay off?'

'Maybe,' I said. I watched the race. Good grief, the energy those kids had; it made me feel very old.

'Or did he think the suicide attempt would make the Department lay off?' Fiona had started thinking about the Giles Trent problem now that it had sexual and emotional aspects. I guess all women are like that.

'I don't know, darling,' I said. 'I'm just guessing.'

'Your guesses can be pretty good.'

'How many married men get an accolade like that from their wives?'

'I'm just lulling you into a false sense of security,' she said.

She looked up to watch the hurdles being positioned for the next race. The bearded headmaster was well in evidence. He had a tape measure. He checked the position of everything and marked his approval or disapproval with nods or headshakes. Fiona watched the children parade until she was quite sure that Billy was not anywhere in the teams. Then she returned to the subject of Trent. 'Giles did it for the sake of his sister. He didn't have to get into it at all, did he? You said the Russian targeted him through the sister.'

'But don't imagine that they hit him when he was cold. Don't think the KGB go to all the trouble they went to without being confident he would buy their proposition.'

'I didn't think of it like that.'

'You think a woman goes after a married man just on the off-chance that he's fed up with his wife? No, she checks out her chances of success.' I'd almost said Tessa but I'd recovered myself just in time.

'What sort of signs would she look for?'

'Some people find it fascinating to think about doing the worst thing they can think of. What would it be like to murder someone? What would it be like to post this stuff off to the Russians? How would it feel to have a vulgar noisy mistress tucked away in a flat in Bayswater? At first they toy with it because it's so crazy. But one day that impossible idea starts to take shape. How would I start to do it, they ask themselves, and step by step the practical planning begins.'

'I take due note of the fact that you haven't told me what signs a woman looks for when she's after a married man.'

I smiled and applauded the winning hurdler.

She didn't let the subject drop. 'You think Giles got beyond the fantasy stage even before the Russians approached his sister?' she asked.

'Maybe not, but he didn't come running into the security office on the day he discovered exactly what his sister's boyfriend did for a living.'

'Because he'd thought about it?'

'Everyone thinks about it,' I said.

'Mistresses, or selling secrets?'

'It's only human to think about such things.'

'So where did Giles go wrong?' she asked.

'He envisaged himself sinning and found he could live with that image of himself.' I took out my cigarettes but the headmaster came over and, smiling, shook his head, so I put them away again.

'And you couldn't live with the image of yourself snuggled up with the noisy girl in Bayswater?'

'You can't have everything,' I said. 'You can't have the fantasies and the reality. You can't have the best of both worlds.'

'You've just blown a hole in the Liberal Party election platform.'

'No one can serve two masters. You'd think even a bean-brained public-school man like Trent would have known that.'

'There was never anything between Bret and me,' said Fiona, and touched my hand.

'I know,' I said.

'Really know?'

'Yes, really know.' I wanted to believe it. It was a failing in me, I suppose.

'I'm so pleased, darling. I couldn't bear the idea of you worrying about me.' She turned to look into my eyes. 'And Bret, of all people… I could never fancy him. When is Billy coming on?'

I looked at the programme. 'It must be the next but one: the junior obstacle race.'

I leaned closer to Fiona and whispered how much I loved her. I could smell the faint perfume of her shampoo as I nuzzled against her hair.

'No one thought it would last,' she said. She hugged me. 'My mother said I'd leave you within six months. She even had a room ready for me right up until Billy was born. Did you know that?'

'Yes.'

'Tessa was the only one who encouraged me to marry you. She could see how much I loved you.'

'She could see how you wrapped me around your finger.'

'What a lovely thought.' She laughed at the idea of it. 'I've always been frightened that some clever little lady will come along and find out how to wrap you around her finger, but I've seen no sign of it so far. The truth of it is, darling, that you're unwrappable. You're just not a ladies' man.'

'What does a ladies' man have to do?'

'You can't be bothered with women. I never worry about you leading a double life. You'd never go to all the trouble needed to tuck that "vulgar noisy mistress" away in Bayswater.'

'You sound like Giles Trent. The other day he told me that Werner Volkmann could never be a double agent because he was too lazy.'

'No one could accuse you of being lazy, my darling, but you certainly don't go out of your way to be nice to women – not to me, not to Tessa, or even your mother.'

I found these criticisms unreasonable. 'I treat women just as I treat men,' I said.

'For goodness' sake, my darling thickheaded husband. Can't you understand that women don't want to be treated just like you treat men? Women like to be fussed over and cherished. When did you ever bring home a bunch of flowers or a surprise gift? It never occurs to you to suggest we have a weekend away.'

'We're always having weekends away.'

'I don't mean with Uncle Silas and the children – that's just to give Nanny a break. I mean a surprise weekend in Paris or Rome, just the two of us in some lovely little hotel.'

I never cease to wonder about what goes on in a woman's brain. 'Whenever I've asked you to come along on a trip, you say you've got too much work to do.'

'I'm not talking about going with you on one of those damned jobs of yours. You think I want to walk around Berlin while you go off to see some old crony?'

'I'll have to go back there,' I said.

'I heard Dicky talking to Bret about it.'

'What did they say?'

It was typical of Fiona's caution that she looked round to be quite sure that no one was in earshot. She needn't have bothered. Some of the parents were talking to the head, some were out in the dark windswept yard calling for their children, while the rest remained in their seats stoically watching the races. 'The D-G apparently said there was no one else experienced enough to send. Dicky said that they'd soon have to wind up the Brahms net. Bret pretended to agree, but Bret won't survive as a Department head without his Brahms Four source. But, for the time being, Dicky and Bret have compromised on the idea that they'll squeeze a couple more years out of him. They think you're the only person who could persuade the network to keep working a little while longer.'