'If I'd known what you were going to do I would have made different plans.'

'I told you. I told you over and over.' She looked down and continued to eat her winter salad as if there was no more to be said. In a way she was right. She had told me time and time again. She'd been telling me for years that she was going to go to Cambridge and get this honours degree in PPE that she'd set her heart on. She'd told me so many times that I'd long since ceased to give it any credence. When she told me that she'd actually resigned I was astounded.

'I thought it would be next year,' I said lamely.

'You thought it would be never,' she said curtly. Then she looked up and gave me a wonderful smile. One thing about this damned business of going to Cambridge. It had put her into an incomparably sunny mood. Or was that simply the result of seeing me discomfited?

It was Gloria's evening for visiting parents. Tuesday she had an evening class in mathematics, Wednesday economics and Thursday evening she visited her parents. She apportioned time for such things, so that I sometimes wondered if I was one of her duties, or time off.

I stayed working for an extra hour or so until there was a phone call from Mr Gaskell, a recently retired artillery sergeant-major who'd taken over security duties at reception. 'There is a lady here. Asking for you by name. Mr Samson.' The security man's hoarse whisper was confidential to the point of being conspiratorial. I wondered if this was in deference to my professional or social obligations.

'Does she have a name, Mr Gaskell?'

'Lucinda Matthews.' I had the feeling that he was reading from the slip that visitors have to fill out.

The name meant nothing to me but I thought it better not to say so. 'I'll be down,' I said.

'That would be best,' said the security man. 'I can't let her upstairs into the building. You understand, Mr Samson?'

'I understand.' I looked out of the window. The low grey cloud that had darkened the sky all day seemed to have come even lower, and in the air there were tiny flickers of light; harbingers of the snow that had been forecast. Just the sight of it was enough to make me shiver.

By the time I'd locked away my work, checked the filing cabinets and got down to the lobby the mysterious Lucinda had gone.

'A nice little person, sir,' Gaskell confided when I asked what the woman was like. He was standing by the reception desk in his dark blue commissionaire's uniform, tapping his fingers nervously upon the pile of dog-eared magazines that were loaned to visitors who spent a long time waiting here in the draughty lobby. 'Well turned-out; a lady, if you know my meaning.'

I had no notion of his meaning. Gaskell spoke a language that seemed to be entirely his own. He was especially cryptic about dress, rank and class, perhaps because of the social no-man's-land that all senior NCOs inhabit. I'd had these elliptical utterances from Gaskell before, about all kinds of things. I never knew what he was talking about. 'Where did she say she'd meet me?'

'She'd put the car on the pavement, sir. I had to ask her to move it. You know the regulations.'

'Yes, I know.'

'Car bombs and that son of thing.' No matter how much he rambled, his voice always had the confident tone of an orderly room: an orderly room under his command.

'Where did she say she'd meet me?' I asked yet again. I looked out through the glass doors. The snow had started and was falling fast and in big flakes. The ground was cold, so that it was not melting: it was going to lie. It didn't need more than a couple of cupfuls of that sprinkled over the Metropolis before the public transportation systems all came to a complete halt. Gloria would be at her parents' house by now. She'd gone by train. I wondered if she'd now decide to stay overnight at her parents', or if she'd expect me to go and collect her in the car. Her parents lived at Epsom; too damned near our little nest at Raynes Park for my liking. Gloria said I was frightened of her father. I wasn't frightened of him, but I didn't relish facing intensive questioning from a Hungarian dentist about my relationship with his young daughter.

Gaskell was talking again. 'Lovely vehicle. A dark green Mercedes. Gleaming! Waxed! Someone is looking after it, you could see that. You'd never get a lady polishing a car. It's not in their nature.'

'Where did she go, Mr Gaskell?'

'I told her the best car park for her would be Elephant and Castle.' He went to the map on the wall to show me where the Elephant and Castle was. Gaskell was a big man and he'd retired at fifty. I wondered why he hadn't found a pub to manage. He would have been wonderful behind a bar counter. The previous week, when I'd been asking him about the train service to Portsmouth, he'd confided to me – amid a barrage of other information – that that's what he would have liked to be doing.

'Never mind the car park, Mr Gaskell. I need to know where she's meeting me.'

' Sandy 's,' he said at last. 'You knew it well, she said.' He watched me carefully. Ever since our office address had been so widely published, thanks to the public-spirited endeavours of 'investigative journalists', there had been strict instructions that staff must not frequent any local bars, pubs or clubs because of the regular presence of eavesdroppers of various kinds, amateur and professional.

'I wish you'd write these things down,' I said. 'I've never heard of it. Do you know where she means? Is it a café, or what?'

'Not a café I've heard of,' said Gaskell, frowning and sucking his teeth. 'Nowhere near here with a name like that.' And then, as he remembered, his face lit up. 'Big Henry's! That's what she said: Big Henry's.'

'Big Henty's,' I said, correcting him. ' Tower Bridge Road. Yes, I know it.'

Yes, I knew it and my heart sank. I knew exactly the kind of 'informant' who was likely to be waiting for me in Big Henty's: an ear-bender with open palm outstretched. And I had planned an evening at home alone with a coal fire, the carcass of Sunday's duck, a bottle of wine and a book. I looked at the door and I looked at Gaskell. And I wondered if the sensible thing wouldn't be to forget about Lucinda, and whoever she was fronting for, and drive straight home and ignore the whole thing. The chances were that I'd never hear from the mysterious Lucinda again. This town was filled with people who knew me a long time ago and suddenly remembered me when they needed a few pounds from the public purse in exchange for some ancient and unreliable intelligence material.

'If you'd like me to come along, Mr Samson…' said Gaskell suddenly, and allowed his offer to hang in the air.

So Gaskell thought there was some strong-arm business in the offing. Well he was a game fellow. Surely he was too old for that sort of thing: and certainly I was.

'That's very kind of you, Mr Gaskell,' I said, 'but the prospect is boredom rather than any rough stuff.'

'Whatever you say,' said Gaskell, unable to keep the disappointment from his voice.

It was the margin of disbelief that made me feel I had to follow it up. I didn't want it to look as if I was nervous. Dammit! why wasn't I brave enough not to care what the Gaskells of this world thought about me?

Tower Bridge Road is a major south London thoroughfare that leads to the river, or rather to the curious neo-Gothic bridge which, for many foreigners, symbolizes the capital. This is Southwark. From here Chaucer's pilgrims set out for Canterbury; and a couple of centuries later Shakespeare's Globe theatre was built upon the marshes. For Victorian London this shopping street, with a dozen brightly lit pubs, barrel organs and late-night street markets, was the centre of one of the capital's most vigorous neighbourhoods. Here filthy slums, smoke-darkened factories and crowded sweat-shops stood side by side with neat leafy squares where scrawny clerks and pot-bellied shopkeepers asserted their social superiority.