'No, I didn't. The number and date have been blanked out. How can you tell?'

She took a biscuit and nibbled it to gain time. 'I'm not sure if I'm permitted to tell you that,' she said.

'It's an investigation, Mrs Hogarth.'

'I suppose it's all right, but I can't give you the details. I can only tell you that when sensitive material like this is circulated, the word processor is used so that the actual wording of its text is changed. Just the syntax, you understand; the meaning is not affected. It's a precaution…'

'So that if a newspaper prints a quote from it, the actual copy can be identified.'

'That's the idea. They don't talk about that very much, of course.'

'Of course. And this is the one that went to the Cabinet Office?'

'Yes. I wouldn't have wasted your time with all that detail if I'd known that's all you wanted. I naturally thought you'd photocopied your own copy and were trying to trace one that had been stolen.' She passed the photocopy to me.

'It's natural that you'd think that,' I said as I put it back into my pocket. 'It was stupid of me not to make it all clear.'

'Oh yes, that's made from your Department's copy,' said Mrs Hogarth.

She got to her feet, but for a moment I sat there, slowly coming to terms with the idea that the document Bret Rensselaer had been given for action was the one copied for Moscow 's KGB archives. I'd gone on hoping that her answer would be different, but now I would have to look the facts straight in the eye.

'I'll come with you to the door,' she prompted. 'We're getting very security conscious nowadays. Would you like to go out through the Number Ten door? Most people do, it's rather fun, isn't it?'

'You're quite certain?' I said. 'No chance you've got it wrong?'

'No chance at all. I checked it twice against my list. I can't show it to you, I'm afraid, but I could get one of the security people to confirm it…'

'No need for that,' I said.

It was raining now and the gardeners had abandoned the idea of planting the roses. They'd put the plants back into their box and were heading towards the house for shelter.

Mrs Hogarth watched them sorrowfully. 'It happens every time they start on the garden. It's almost like a rainmaking ceremony.'

In the front hall of Number Ten there was a bored-looking police inspector, a woman in an overall distributing cups of tea from a tray, and a man who opened the door for me while holding his tea in one hand. 'I appreciate your help, Mrs Hogarth,' I said. 'I'm sorry about not having the official chit.'

She shook hands as I went out onto that famous doorstep and said, 'Don't worry about the chit. I have it already. It came over this morning.'

'It's our anniversary,' said Gloria.

'Is it?' I said.

'Don't sound so surprised, darling. We've been together exactly three months tomorrow.'

I didn't know from what event she'd started counting, but out of delicacy I didn't enquire. 'And they said it wouldn't last,' I said.

'Don't make jokes about us,' she said anxiously. 'I don't mind what jokes you make about me, but don't joke about us.'

We were in the sitting room of an eleventh-floor flat near Netting Hill Gate, a residential district of mixed races and lifestyles on the west side of central London. It was eight-thirty on a Monday evening. We were dancing very very slowly in that old-fashioned way in which you clasped each other tight. The radio was tuned to Alan Dell's BBC programme of big-band jazz, and he was playing an old Dorsey recording of Tea for Two'. She was letting her hair grow longer. It was a pale-gold colour and now it was breaking over her shoulders. She wore a dark-green ribbed polo-neck sweater, with a chunky necklace and a light-brown suede skirt. It was all very simple, but with her long legs and generous figure the effect was stunning.

I looked around the room: gilded mirror, silk-lined lamp-shades, electric-candle wall lights and red velvet hangings. The hi-fi was hidden behind a row of fake books. It was the same elaborate clutter of vaguely nineteenth-century brothel furnishings that's to be seen in every High Street furniture shop throughout Britain. The curtains were open, and it was better to look through the window and see the glittering patterns of London by night. And I could see us reflected in the windows, dancing close.

Erich Stinnes was thirty minutes overdue. He was to stay here, with Ted Riley in the role of 'minder'. Upstairs, where Stinnes would spend most of his time, there was a small bedroom and study, and a rather elaborate bathroom. It was a departmental house, not exactly a 'safe house' but one of the places used for the clandestine accommodation of overseas departmental employees. It was the policy that such people were not brought into the offices of London Central. Some of them didn't even know where our offices were.

I had come here to greet Stinnes on his arrival, double-check that Ted Riley was in attendance, and take Stinnes out to dinner to celebrate the new 'freedom' he'd been so reluctantly granted. Gloria was with me because I'd convinced Bret, and myself, that her presence would make Stinnes more relaxed and soften him up for the new series of interrogations that were planned.

'What happened about that chit for Number Ten?' I said as we danced. 'Your friend over there said she'd already had one. How could she have got a chit? I didn't even apply for one.'

'I told her a tale of woe. I said that after it was all signed and approved I'd lost it. I told her that I'd get the sack if she didn't cover for me.'

'You wicked girl,' I said.

'There's so much paperwork. If we didn't bend the rules now and again, we'd never get everything done.' As we danced she reached out and stroked my head. I didn't like being stroked like a pet poodle, but I didn't complain. She was only a child and I suppose such corny little manifestations of endearment were what she thought appropriate to her role as a femme fatale. I wondered what she'd really like me to do – bury her in long-stem red roses and ravish her on a sable rug in front of a log fire in the mountains, with gypsy violins in an adjoining room?

'You're worrying about Bret Rensselaer, aren't you?' she asked softly.

'You're always saying that, and I'm always replying that I don't give a damn about him.'

'You're worried about what you discovered,' she said. She accepted my little bursts of bad temper with equanimity. I wondered if she realized how much I loved her for doing that.

'I'd feel a hell of a lot better without having discovered it,' I admitted. The music came to an end and there was some chat about trumpet and the tenor-sax solos before the next record started: Count Basie playing 'Moonglow'. She threw her head back, twisting her head so that her long pale hair flashed in the light. We began dancing again.

'What are you going to do about it? Report it?' she asked.

'There's not much I can report. It's all very slight and circumstantial except for the Cabinet memo, and I'm not going to stride into the D-G's office and report that. They'll want to know why I didn't report it when I first got it. They'll ask who gave it to me, and I don't want to tell them. And they'll start digging deep into all kinds of things. And meanwhile I'll be suspended from duty.'

'Why not tell them who gave it to you?'

'All my sources of information and goodwill would dry up overnight if I blew one of them. Can you imagine what sort of grilling Morgan would arrange for the man who'd got hold of Bret's copy of the memo?'

'In order to get rid of Rensselaer?'

'Yes, to get rid of Rensselaer.'

'He must be a wonderful man, your contact,' she said wistfully. I hadn't told her anything about Posh Harry and she resented my secrecy.