In my experience there really is only one thing worse than falling out of love, and that is being fallen out of love with - being fallen out of love with fills you with all the horrors of abandonment, you are contemptible to yourself and therefore, you assume, contemptible to others, and consequently even more contemptible to yourself, and really you have no choice but to go away and commit some form of temporary suicide. Well, falling out of love is an altogether grubbier affair, there are no blinding rages or weeping breakdowns to obliterate what is really one long act of procrastination - you look at the only recently adored face, so sweet, so trusting, so vulnerable, and you think to yourself, how could I bring pain to that? And what you also think is, why can't I hurry up and get it over with, get her over with? The longer she's around, the more you hate the sight of her - actually, it's worse than that, what you feel above all else is nausea - you are nauseated by her for having fallen in love with you, and by yourself for having fallen in love with her, and terrified of the pain you're going to cause her - how many men have murdered a woman because they couldn't bear to hurt her?

Do women feel the same way? All the women who fell out of love with me seemed to find the pain they were causing bearable, though they did say, now and then, that they hated, really hated, seeing me so unhappy, though that didn't stop them seeing me.

Heading up Holland Park Avenue the other day for a cup of coffee, I passed a man who reminded me of someone. He was wearing a trilby with a plastic bag over it, had a spiky grey beard, a yellow mackintosh, baggy blue trousers, white socks and sandals - there was an element of contradiction in his get-up, it was raining, which made sense of the mackintosh and the trilby, but nonsense of the white socks and the sandals. He looked very eccentric, but not poor - all these garments looked as if they'd been selected from a wardrobe, rather than assembled by chance from the tips and dumps that fall in the way of a tramp. He was about my age, I should think, perhaps a tad older, in his early to middle 70s. As we passed each other, he turned his face towards me and gave me a smile, and it was this, the smile, that sent a shiver of recognition through me, and made me stop and look after him. I half expected him to stop, too, I was sure he'd seen something in my face that had given him a momentary glimpse backwards, about 50 years backwards, actually, to Cambridge, to a large redbrick house on Station Road where he - or the man I took him to be - and I had taught English to foreigners.

The name of the man I took him to be was Manfred Hendow, and he had then exactly the same sort of beard, and - as I've said - the same sort of smile as the elderly man on Holland Park Avenue - a mystical smile, with a hint of a sneer in it. Yes, he was full of contempt, he told me, but most of it was for himself - he'd had a breakdown when an undergraduate at Oxford, an emotional and intellectual breakdown, as a result of which he'd got an inferior degree, but more crucially, had lost his ambition, his will to act in life. He'd read Russian, his family was Russian, and perhaps his fatalism, his depressive taint, that made life in all its manifestations seem futile, was in his genes. On the other hand, he'd been to India for a while, and had learned there the value of detachment, the withdrawal of the spirit from the ordinary clamours of life. He spoke in a measured, slightly rhythmical voice, and his eyes, dark brown, were usually lifeless, as if willed to be so.

Although he was only a few years older than me, he seemed to me vastly more experienced, vastly more complex than I was. It was his loneliness, his calm acceptance of failure, his inert postures - when he wasn't teaching, he would lie on the common room's only sofa, his sandalled feet crossed on the arm at one end, his head resting on the arm at the other, his hands folded across his chest, corpse-like. There were several middle-aged women teachers, and two or three old men on the staff; when they came into the common room for their breaks he would turn his head slightly, and wonder if they wanted the use of the sofa - they invariably declined, as if acknowledging that it belonged in some way to him, he had an unchallengeable claim on it - of course it's quite hard to say to a man who hasn't actually shifted his body an inch that, yes, you'd like him to shift it completely, you'd like to sit where he was lying, so make way please, and hurry up about it - but the truth is that I don't think anybody resented his occupancy. Several members of the staff were both forthright and simmeringly disappointed by life, and quarrelsome with each other, but Manfred on the sofa, elongated in a melancholy glow, was in some way out of their reach, like a saint, or half the Arundel tomb.

We didn't exactly develop a relationship - anyway, not a friendship. We talked quite a lot about books. He was interested in Buddhism, particularly Zen. I suppose I talked a lot, in my florid manner of the time, about all the novels and poetry I considered to be overrated. I'd come to Cambridge to be a Leavisite. "Against life" was the phrase I tended to use of almost anything in, say, the 20th century that hadn't been written by DH Lawrence. So I'd practise my Leavis positions on him, and he would meditate in a weary sort of way, and sometimes in a dreary sort of way, on the uselessness of being, the transcendence of indifference, and so forth.

One evening he invited me back to supper in a cottage he was renting in Little Shelford, a few miles outside Cambridge. We cycled there together, left our bikes at a gate, and walked across the field towards a dimly lit kitchen where I could see, through the window, a young woman doing cooking-like things, with a baby at her hip. He'd never mentioned the existence of a woman in his life, let alone a baby. It had never occurred to me that anyone of roughly my generation could be in possession of either - I was still a virgin, after all, and though I believed that sex would be immediately punished by offspring, I yearned for it, but feared that however long I lived, I'd never be old enough or mature enough to earn it. The woman, small and neat and lively, with a slight but sturdy figure and a squawking but not unattractive voice, was about his age, a few years older than me. He introduced us to each other with a gesture that was like a dismissal, not just for me, but for the other two. "This is Simon Gray. And that's Donna. The baby's name is Tertius." And he sat down at the table, folded his hands and closed his eyes, looking as he so often did in the common room, self-excluded. I didn't know what to say, but nevertheless said it. "Oh. I didn't know you were married." Donna squawked a laugh, Manfred opened his eyes in amusement.

I wish I could remember the evening, the dinner, the conversation over it, but I don't really, beyond the fact that apart from eating with us, Manfred wasn't really there - he behaved as if he'd effected a substitution, as if he'd brought me along to fill in for him, and I suppose I must have done because I do recall I watched as Tertius was bathed, and then as he was breast-fed, which I took to be an immense privilege from which I mainly averted my eyes. It was such an open and natural act from which I should have been kept away because I brought to it a prurience. I was conscious of the pull on her breasts, the full nipples, the busy, greedy mouth - and Donna's face, her expression calm, her eyes radiant as she rested them on me and asked me questions in her squawking, abrasive voice but about what I no longer know - she had a direct, uncomplicated way of asking, and I liked it because I could answer her reasonably directly, and didn't feel I had to make the best of myself. Now and then Manfred drawled in and offered her a fact about me that was also for me - "Simon likes teaching foreigners English. And they seem to like him, the pretty ones. But I don't know whether he likes them. He doesn't do anything about them. He thinks it would be wrong." He made me feel like one of the students, with too feeble a grasp of English to understand what he was saying about me, but suspecting that it was contemptuous. Yes, I was suspicious. Nothing was right about all this ...

I can no longer follow the stages that led to my being ensconced in a flat in Harley Street, on the run from St John's College, Cambridge, which had given me a writing fellowship the main condition of which was that I had to go abroad - but I wasn't abroad, I was in Harley Street and not writing anything, not even replies to sent-on letters from St John's College, Cambridge, asking where I was - the only bits I can remember are the bits I don't want to remember: our first fuck, for instance. Actually, it wasn't her first fuck, obviously, as she had a baby by what was also evidently not her first fuck - she had a long and turbulent history with men, she used to entertain me with it. I think I've put down that she had a slightly quacking voice, but did I mention that she laughed in husky yelps that were almost like screeches? - her voice sometimes made me grit my teeth, and yet I fell in love with it, I came to find it attractive and exciting, no young woman I'd met before had a voice like it, so uninhibitedly dissonant, but then I'd never met a young woman who talked about the kind of things she talked about, and in a voice like that. Before Harley Street, before she'd left Manfred, long before our first fuck, so back in Cambridge therefore ...

Back in Cambridge she would sit on my one chair in my room in Jesus Lane, and I would sit on the edge of the bed, a double bed oddly enough, as only Trinity students - young, single males - ever occupied this lodging house, which was owned by a large, bald Pole with a loud voice. His plump younger wife, sweet-voiced and English, cleaned our rooms and made our breakfast - they were a very kind couple, considerate and helpful, though a bit mean with bath water unless you took your bath cold, but then gas heating was expensive - and the breakfasts were ample, lots of toast and butter and jam and tea, bacon and eggs - actually, the eggs were a problem during my first year, there was sometimes quite a lot of hair underneath and around them, like a rather scanty nest - when I came back for my second year she had taken to wearing a rubber shower cap, so obviously she had a scalp condition, possibly alopecia.

One of my co-lodgers was a research student writing a history of mathematics, a 10-year project, he would say frequently, not counting the three he'd already spent on it. He was from the north, so much from the north that he really did think southerners were effete, lazy, corrupt - not far wrong in my case, although I was also miserable. Yes, effete, lazy, corrupt and miserable is a reasonable thumbnail of my spiritual and/or moral state at the age of 20, in my first year at Cambridge, while a reasonable if external thumbnail of Len - is Len his real name or do I just think basically all northerners of that period were called Len, after Len Hutton? - would be dour, hard-working, moralising and miserable. So really there we were, the pair of us conforming exactly to each other's stereotypes as we bantered miserably away across the breakfast table 50 years ago.

Like me he spent every evening at the cinema but, unlike me, he went actively, with an alert eye and a sharp ear and an encyclopedic knowledge of actors, directors, screenwriters, even editors and cameramen, and yet he seemed to despise every film he saw, or perhaps he talked only about the films he despised, unwilling to contaminate the films he liked, loved even, by discussing them with me. We had many breakfasts together, three years of term-time breakfasts, in fact, and our conversations would go something like this ... "Saw a film you'd like last night," he'd say. "Yes, you'd like it." "Really, which one?" "The John Ford at the Regent." "Oh," I said, "The Searchers. Yes. I've seen it. I liked it very much." "There," he said. "Knew you would. Knew you would. Said to myself, that's the film for you."

I got his drift, of course. "And what did you hate about it?" "Everything," he said triumphantly. "Great big phoney bloated artistic ..." Artistic was one of his most scathing words, he somehow slipped the hint of an "s" in before the first "t", making it sound almost lavatorial, Arse-Tist-Tuck. "Absolutely not," I said. "Epic, poetic, humane ..." etc - I saw The Searchers again, about five years ago, and about halfway through I found myself recalling Len and his judgment, and from then on it was as if I had double vision, one eye mine and the other Len's, completely at odds with each other but both of them true, because actually The Searchers did seem simultaneously epic and bloated, humane and phoney, poetic and Arse-Tist-Tuck ...

Well, Len got into this because I can't bear, when it comes to it, to struggle my time with Donna back into my life, but having started on it, I can't seem to find a way of not going on with it, either - stalled is what I am, stalled. Try Q&A ...

There's a film called Q&A about a homicide detective who is also a homicidal detective in that the suspect he is interrogating he ends up killing, he was played by an actor with an odd voice that didn't go with his face, which was saturnine, a beaky nose and dark, liquid eyes, altogether an impressive and glamorous figure of the Hispanic-American type until he spoke, or piped rather - he's been in quite a few David Mamet films, all convoluted plot and rhythmic, demotic dialogue, you almost nod your head to it, your poor old head which is befuddled by all the twists and turns and surprises of a plot so complicated ...

Did you love her?

I remember anger, bitterness, hopelessness, despair, so yes.

Did she love you?

Yes. Until ...

Until?

We had sex.

Bad sex then?

No, worse than that.

Can you be more precise?

Well, actually it was no sex - a lot of physical activity but no actual sex.

Can you be more precise?

It was in a room in Harley Street.

Oh, it was some sort of medical thing then, was it?

No. I was living there. This was after I'd left Cambridge. A flat at the top of the house. It belonged to a surgeon, a very nice man. Donna was working as his receptionist. He let me have this flat for a very small rent. For Donna's sake, I suppose. As I was thought to be her boyfriend.

But you weren't?

I was until...

You had no sex with her?

That's it. Yes.

What form did this no sex take?

When I had peeled my trousers down to my knees, and had rolled my underpants down to my trousers' crotch, I lay on top of her and bucked about, yelping.

Why?

I didn't know what else to do, obviously. I was a virgin.

A 25-year-old virgin?

Right.

Unusual, possibly?

Don't know. This was 1961, remember, before the Beatles' first LP and so forth.

And so you were anatomically ignorant?

Yes.

But you're a doctor's son.

Yes.

Couldn't you have consulted a book?

I did, but it didn't make much sense. I suppose I could have copied a diagram but I could scarcely have held it in my hand when I got on top of her, like a road map.

Was she naked?

Yes. She took all her clothes off, and let down her hair, talking all the while in her slightly quacking voice, brightly and eagerly, how we'd waited long enough, and now Manfred was out of the picture, and as little Tertius - at this stage quite a big Tertius, at four years old - was so happily settled with her parents - and we had the use of this flat and this nice double bed - I wanted her to undress for ever and quack for ever, to put off the moment of reckoning.

She didn't know you were a virgin?

No.

Would it have been better if you'd told her?

I expect so, because the next time she showed me what I was expected to do, and how and where to do it, and after that it got easier and easier, and by the end I would really have enjoyed it if she hadn't hated it so much.

Why did she hate it?

Probably never got over our first time, my first time, to be exact, she never got over my first time. She liked older men, really, older than herself and much older than me - men who took charge and ran the show. Even when I got used to it, I never ran the show, I got into the habit of waiting for instructions.

Why didn't you warn her that you were a virgin?

Too embarrassed, obviously. And also before I met her there was another girl, an undergraduate, who was famous for having slept with a man who was famous for getting sent down for smoking pot. She came around regularly in the afternoon for tea and conversation. One afternoon, before I'd begun to make tea on the little gas ring beside the fire, she said, "I keep wondering when you're going to ask me to go to bed with you." I was very calm, though parts of me stirred. "Yes," I said, "I was wondering that, too."

She was a very shapely, round girl, Jewish, sexy and yet maternal, with russet hair and pouty lips - a firm chin withal. Her father was a doctor, with a practice in London, Goldhawk Road, and she was reading history. She had been very much in love, she'd told me, with the chap who'd got sent down for pot smoking - I should point out pot smoking was at that time very unusual in Cambridge, a truly exotic offence, so he was a legendary figure - undergraduates of both sexes who didn't smoke pot themselves because they didn't want to get sent down liked to have their names linked with his - as did Esther. That was her name. Esther. I think there was something in front of it - Emma Esther - sounds wrong, Anne - or Anesta - yes, Anesta, not sure if that's how it was spelled, but I'll stick with it.

Anesta was very proud of having been Pot-boy's lover, she liked to say the word "lover" in confessional sentences - "My mother would never have accepted my having ..." - she always said his name in full, not Ned or Japes or whatever, but Michael Stumpfield, let's say: "Everybody knew that Michael Stumpfield was my lover"; "My mother never accepted that I was Michael Stumpfield's lover." So we had tea and conversations about her being the lover of Michael Stumpfield, of whom of course I was not only jealous for sexual reasons, but envious for life reasons. My body was full of hope but my mind, or wherever the will is lodged, was full of confusion and despair, because it knew that the "I" of me - what Kant calls "the synthetic unity of apperception" - was too timid to make even a shy move towards getting what my body wanted - on top of which there was the not completely suppressed suspicion that when it came down to it I didn't really like her very much, not only because there was too much Michael Stumpfield, but also too much breasts, which were prominently covered and gave me a headache until that afternoon when she said, "I keep wondering when you're going to ask me to go to bed with you." And I said, "I was wondering that, too" - but what I was really wondering was whether this was a variation on Michael Stumpfield's opening gambit, had he perhaps said, "I expect you're wondering when I'm going to ask you to go to bed with me" - or more casually, more confidently, more pot-headedly, "I expect you're wondering when I'm going to take you to bed." Anyway, the way she said it didn't sound right to me, even to me, who'd never heard words like these spoken before, except in films with subtitles. Nevertheless she took off her clothes in a modest and stately fashion, as far as I could see, I partly averted my eyes, which I believed to be the polite response, and at some point, before she was completely naked, I explained my - our - situation. I hope I didn't actually say, "So be gentle with me" but I suppose that was the implication - anyway, as soon as I broke the news she got dressed again.

Didn't she say anything?

Well, she laughed. As I've said, she was quite a big girl, soft and curvy, and when she laughed her breasts seemed to laugh too, bouncing and bobbing to her laughter. She liked my jokes, which I now see was the best thing about her.

Did she think this was one of them?

No, it wasn't that sort of laugh. When she was dressed and having a cup of tea, she explained that she just didn't want the responsibility.

The responsibility of taking your virginity?

Presumably. From then on she let me nuzzle her whoppers.

Which is to say?

That she used to let me sit on her lap like a very large baby and suck her nipples and when I got excited and wanted more she would stroke my head and murmur, "No, no, I'm still not ready, still not ready, Mr Jumblenose."

Mr Jumblenose?

A private joke.

Sometimes you wanted to kill her. By the end you were sick to death of her breasts, you associated them with pain, hunger, torment - they were a form of torture, really. Lust aroused and unsatisfied.

That's not a question.

No. It's the answer you might not have given. Tell me ...

Mmm?

What aroused your lust in the years of your adolescence and early manhood, before you suckled at Michael Stumpfield's lover's whoppers?

Oh, the usual stuff - a flash of thigh, stocking tops, the curve of a medium-sized breast in profile, a nipple erect in a diaphanous bra, the slope of stomach into a tangle of hair, handcuffs, Hank Janson covers, The Collected Works Of Immanuel Kant.

Pornographic clichés, you mean?

Absolutely.

Women as objects and pornography?

Ideally. I'm only talking ideally. Hence Kant.

Are you ready to go back to Donna?

No.

The double bed - you were sitting on the edge of it, as you did with Anesta, and like Anesta, she was sitting on your desk chair...

... and like Anesta she told me about her past, about which I remember nothing except that she'd been at art school for a short time and had been promiscuous. For me, at that time in my life, promiscuous was undoubtedly one of the most exciting words in the language. I was only 21, after all, and so ignorant of sex that its vast vocabulary, of which I had some command, had no proper - ie, "lived", as we Leavisites, worshippers of DH Lawrence and the dark Gods of the Unconsciousness, used to say - no proper "lived" content. In the following months, many, many months, about 48 of them, in fact, our relationship developed, matured, ripened, until it imploded in my first fuck, as reported above. This was Cambridge just past the middle of the last century - we did things differently there. At least I did.

· This is an edited extract from The Last Cigarette (The Smoking Diaries: Volume 3), by Simon Gray, published next month by Granta at £14.99. To order a copy for £13.99, including UK mainland p&p, call 0870 836 0875 or go to theguardian.com/bookshop.