He had quite often, in the past, when she was being more than usually irritating, had fantasies about her death. She hurtled over cliffs in flaming cars or was brutally murdered on her way to the dry cleaners. But Henry was never actually responsible for the event. He was at the graveside looking mournful and interesting. Or he was coping with his daughter as she roamed the now deserted house, trying not to look as if he was glad to have the extra space. But he was never actually the instigator.

Once he had got the idea of killing her (and at first this fantasy did not seem very different from the reveries in which he wept by her open grave, comforted by young, fashionably dressed women) it took some time to appreciate that this scenario was of quite a different type from the others. It was a dream that could, if he so wished, become reality.

One Friday afternoon in September, he thought about strangling her. The Wimbledon Strangler. He liked that idea. He could see Edgar Lustgarten narrowing his eyes threateningly at the camera, as he paced out the length of Maple Drive. `But Henry Farr," Lustgarten was saying,`with the folly of the criminal, the supreme arrogance of the murderer, had forgotten one vital thing. The shred of fibre that was to send Henry Farr to the gallows was -"

What was he thinking of? They didn't hang people any more. They wrote long, bestselling paperback books about them. Convicted murderers, especially brutal and disgusting ones, were followed around by as many paparazzi as the royal family. Their thoughts on life and love and literature were published in Sunday newspapers. Television documentary-makers asked them, respectfully, about exactly how they felt when they hacked their aged mothers to death or disembowelled a neighbour's child. This was the age of the murderer. And wasn't Edgar Lustgarten dead?

He wouldn't, anyway, be known as the Wimbledon Strangler, but as Henry Farr, cold-blooded psychopath. Or, better still, just Farr, cold-blooded psychopath. Henry liked the idea of being a cold-blooded psychopath. He pictured himself in a cell, as the television cameras rolled. He wouldn't moan and stutter and twitch the way most of these murderers did. He would give a clear, coherent account of how and why he had stabbed, shot, strangled, gassed or electrocuted her. `Basically," he would say to the camera, his gestures as urgent and incisive as those of any other citizen laying down the law on television, basically I'm a very passionate man. I love and I hate. And when love turns to hate, for me, you know, that's it. I simply had no wish for her to live. l stand by that decision." Here he would suddenly stare straight into the camera lens in the way he had seen so many politicians do, and say, `l challenge any red-blooded Englishman who really feels. Who has passion. Not to do the same. When love dies, it dies."

Hang on. Was he a red-blooded Englishman or a cold-blooded psychopath? Or was he a bit of both? Was it possible to combine the two roles?

Either way, however he did it (and he was becoming increasingly sure that it was a good idea), his life was going to be a lot more fun. Being a convicted murderer had the edge on being a solicitor for Harris, Harris and Overdene of Blackfriars, London. Even Wormwood Scrubs must have more to offer, thought Henry as he rattled the coffee machine on the third floor, than Harris, Harris and Overdene. It wouldn't be so bad, somehow, if he was any good at being a solicitor. But, as Elinor was always telling him, Henry did not inspire confidence as a representative of the legal profession. He had, she maintained, a shifty look about him. `How could you expect anyone to trust you with their conveyancing?" she had said to him, only last week. `You look as if you've only just been let out on parole!"

Glumly, Henry carried his coffee along the dark corridor towards the stairs that led to his office. `Office" was a grandiose term for it really. `Cupboard" would have been a better description. It was a room about eight to ten feet square, offering, as an estate agent with whom Henry was dealing had put it, `a superb prospect of a ventilator shaft". It was, like so many other things in Henry's life, more like a carefully calculated insult from the Almighty than anything else.

He would give himself a treat today. He would go up in the lift. He stabbed angrily at the button. Mr Dent from the third floor, who was waiting by the lift doors, looked at him narrowly. `Can't you tell -" his eyes seemed to say, `that I have already pressed it? Surely you realize that when the button is illuminated someone has pressed it?" Henry, before Dent was able to start talking to him about lifts, weather, the Law Society or any of the other things that Dent usually talked about, headed for the stairs. He pushed open the door and, as he put his foot on the first step, experienced a revelation comparable to that undergone by Newton in the orchard or Archimedes in his bath.

He could kill Elinor, very easily and no one need know. The implications of this were absolutely breathtaking. No one need know. He said it aloud to himself as he trudged up the stairs. No one need know. Of course. No one need know.

Every minute of every day people were being murdered. Hundreds of people disappeared without trace every year. No one ever found them. The police were all, as far as Henry could see, totally incompetent. They spent their time hiding behind low stone walls and leaping out at motorists travelling in bus lanes. They liked people like Henry. People like Henry, white middle-aged men who lived in Wimbledon and had one daughter, were their idea of what British citizens should be. One young constable had come to the house last year when they had been burgled and, very laboriously, had written the details of the crime into a book. He had looked, Henry thought, like a gigantic blue infant, a curious cross between cunning and naïveté a representative of an England that was as dead as the gold standard. Henry had tried to tempt him into making a racist statement by announcing that he had seen a black person outside the window two weeks ago, but all the constable had said was `You don't see many coloureds in this part of Wimbledon." He said this almost with regret, in the tones of a disappointed birdwatcher searching for the great crested grebe.

Nobody would ever suspect Henry. Because _ he was well aware _ most people thought he was something called a Nice Bloke. Henry was never quite sure what being a nice bloke entailed _ it certainly wasn't much to do with behaving scrupulously well towards one's fellow man. If it meant anything at all it probably meant other people thought you were a bit like them. To most of those who knew him Henry was just eccentric enough to be terrifyingly normal, and even his carefully calculated bitterness, the quality of which, on the whole, he was most proud, had become, in early middle age, a Nice Dry Sense of Humour.

I'll give them nice dry sense of humour, he thought savagely as he came out on to his floor and lumbered towards room 4038, I'll give them nice dry sense of humour and then some. I'll give them the real Henry Farr, and he won't just be making witty little remarks about the London orbital motorway either.

Of all Elinor's friends he was the least likely to be suspected of her murder. She had, even at their wedding, surrounded herself with people, nearly all of whom were interesting enough to warrant the close scrutiny of the police. Many of them, to Henry's horror, openly smoked drugs. One of them wore a kaftan. Two wore sandals. And they still trooped in and out of his house occasionally, looking at him pityingly, as they talked of foreign films, the latest play at the Royal Court and the need for the immediate withdrawal of armed forces from Nicaragua. Sometimes they sat in the front room reading aloud from the work of a man called Ian McEwan, an author who, according to Elinor, had `a great deal to say" to Henry Farr.

Oh yeah, thought Henry grimly as he passed 4021a, his coffee threshing around dangerously in its plastic beaker, and Henry Farr had a great deal to say to Ian McEwan as well.

The trouble was, of course, that among Henry's sort of person, a rugby-playing surveyor, for example, or the kind of dentist like David Sprott who wasn't afraid to get up on his hind legs at a social gathering and talk, seriously and at length, about teeth, he was considered something of a subversive. At their wedding, all those years ago, his friends, all of them even then in suits and ties, had nudged each other when he rose to answer his best man. `Go on then," he could see them thinking, be a devil!" But as his eyes travelled across to Elinor's crowd, with their frizzy haloes of hair, their flowered dresses and carefully arranged profiles, he realized that there was nothing he could think of to say that would persuade them he was anything other than a boring little man.

In Rush's home they found, among other things, a detailed account of his poisoning activities. It was this diary, made available to the coroner's inquest, that closed the affair of the Wimbledon Poisoner. When it was published a few years later (to form the basis of a very successful stage play called, simply, D. I. Rush) it caused something of a sensation. People talked about the banality of evil, about the lessons for all of us in Rush's ramblings and Henry read bits of it, out loud, to Elinor, when the more decent parts of it were published in the Sunday papers.

November 3rd 1987 Morning overcast. In the afternoon it rained. I put 0.2 grains of gelsemium in a bun and tried to feed it to the fish. They didn't seem to want it. In evening hoovered spare bedroom.

It was hard, from the papers, to work out which crimes of Rush's were fantasy. Even a year after his death no one was quite sure how many people he had killed. The natural tendency, of course, was to give him credit for every abdominal disturbance, polyneuritis, seizure, fit and remotely questionable disease in the Wimbledon area for the past few years. He had drawn pictures of some of his victims, and in the downstairs broom cuPboard was an electoral roll with a skull and crossbones by the names of at least half of the inhabitants of Maple Drive _ which proved, as Henry pointed out to Elinor, that he wasn't all bad. His mother, it transpired, was a schizophrenic who, by a coincidence that turned out to be just that, lived very near to Henry's mother. Rush was, of course, a monster, but in the course of time he became another sort of monster. A more graphic creature altogether. People who had known him spoke of the strange look in his eyes, of the aura of evil that surrounded him, and many said he had for some years been practising devil-worship. He was said to have heard voices, to have stalked and raped young women and, in the words of one profile, `to have always been alone". Nobody, for some reason, asked Henry about him. Nobody ever mentioned the fact that he was incredibly boring. Being boring didn't, somehow, go with being a mass poisoner and psychopath.

In the course of time people forgot about the Wimbledon Poisoner. He went into history, along with Maltby and Seddon and Maybrick and Lafarge and the rest of them. And they forgot about Henry; it seemed extraordinary, really, that they had ever been able to remember him. He was quoted, briefly, in one paper, on the subject of Rush, but the newspapers, to Henry's surprise, were remarkably ill-informed about the true facts of the case. The journalists who hung around Maple Drive and drank in the Dog and Fox were, almost to a man, highly incurious people.

And in the course of time Henry, too, forgot. He forgot more things than he had already forgotten. He forgot about poisoning, or not poisoning, his doctor, his dentist, his wife's psychiatrist, his ninety-two-year-old neighbour, his publisher (he had come now to think of Karim Jackson as his publisher, and even boasted to neighbours about `going up to London for a chat with his editor") and he forgot not only whether he had or had not poisoned any of these people but even whether he knew who they were or where they had come from. He lived very, very quietly.

He forgot about Wimbledon too, although he continued to live there. He forgot about Everett Maltby and Everett Maltby's wife and Everett Maltby's trial. He forgot about world affairs and local affairs. He forgot about the seasons and the stars and the winds and the rains and almost everything that he didn't absolutely have to remember in order to pay his mortgage, feed and clothe his wife and daughter and get reasonably drunk three nights out of four.

But he did not forget about the time he tried to murder his wife.

It was, of course, about the most interesting thing he had done. Or, to be more precise, nearly the most interesting thing he had done, since he had never actually done it. It was in his mind when they went to bed and when they rose in the morning and it coloured every individual way he looked at her. Because, of course, now he was not burdened with the intolerable weight of having to go through with it, it was, once again, a delightful possibility. If she showed signs of interest in a holiday with Club Mediterranée, for example, or an ill-thought-out fondness for the work of some young radical playwright, there was the possibility, close to hand, of dropping into the Fulham Armoury, buying a hand gun, and simply blowing her head off, one Saturday morning, just before he departed for Waitrose. The more he entertained this possibility, the better behaved she seemed to be, until about a year or so after he had first decided to kill her he realized, with dumb wonder, that they hardly ever argued, that their friends (they seemed to have acquired quite a lot of friends) were pointing them out as a model couple. And it was then that he thought quite seriously of telling her about the time he tried to give her Chicken Thallium. But he never did. Somehow saying the thing out loud would have had a quite unreasonably large impact on their marriage and, as certain adulterers go quietly to their graves with a secret, so Henry Farr hugged his to himself.

One night, about a year after everyone had been talking about the Wimbledon Poisoner, when he was long forgotten, when Maisie had suddenly grown miraculously taller and thinner, when Henry's office had become an almost restful, neutral place of pilgrimage, when Elinor had acquired a whole new range of obsessions and phrases and Henry hadn't even noticed them, they were lying in bed, under their separate duvets, when she suddenly said to him, `Did you ever try to kill me?"

Henry did not reply.

`There was a time," she went on, `when I really thought you might be =="

`Really?" said Henry in what was almost genuine surprise. `Oh yes!"

`When was that?"

She stirred under the duvet. He hoped she wasn't going to come over to his side of the bed. Henry liked his side of the bed. It felt safe and warm. He heard her click her teeth, a sure sign that she was thinking.

`Oh ages ago == I don't remember =="

`Was it == when the poisoning == started?"

`No," said Elinor, `it was just before all that. One Saturday. Here. There was such a bad feeling in the house."

`Yes =="

`And then poor old Donald =="

Henry coughed. He didn't want to think about Donald. `How was I going to do it?"

`I don't remember."

Henry turned over and listened to the wind on Wimbledon Hill.

`Well," he said, `suppose =="

`Suppose what?"

`Well == suppose the balance of my mind was disturbed sort of thing == and suppose =="

`Suppose what?"

`Suppose I did == well == only once, of course == get this == mad urge == to == do away with you =="

Elinor sat up in bed. Henry stayed very still.

`How do you mean?"

`Well == I don't know == suppose == well, say we'd been having a row and then we were walking == well, near a cliff, say == and I had this urge to == push you off == say =="

`And what then?"

`Well == suppose == you know == I == had a go sort of thing == you know? What would you == er == do?"

`I,d divorce you," said Elinor, `and I'd phone the police and have you sent to prison."

`Fine!" said Henry.

There was another pause. Eventually she slid down to a supine position in the bed. But he could tell from the tense quality of her stillness that she was not asleep.

`I just wondered!" he said, brightly.

`Because you don't want to kill me, do you Henry?" she said.

`Oh no!"

Elinor coughed. `Good," she said.

He heard her snuggle further down into her duvet.

`You couldn't really say anything else, could you?" she said.

`No," said Henry.

Then she stirred in a lazy way and yawned. `I'm very strict about things like that!"

`I know," said Henry.

The silence was of a different quality now. It was restful, autumnal, like the season, like the leaves on the plane tree outside, that were turning, as they had turned a year ago when they were both different people, as they would be tomorrow.

`You can't go round murdering people!" said Henry. `It's just not on!"

Elinor chose not to answer this uncontentious remark. The pause between them lengthened, and then, in the last moments that preceded sleep she spoke again: `You think I'm stupid," she said, but I'm not. I know all about you, Henry. And I'll tell you one thing about us. It's till death us do part. That's the way it is. Right?"

`Right!" said Henry.

She was snoring quite soon after that, but Henry lay awake for a long time, staring into the darkness, waiting for sleep that would not come. He thought about Elinor, and why he was still with her and what it would be like in the weeks and months and years to come. If there was one single thing that she had that was worth something, it was her mysterious quality. She was so hard to explain. He still didn't quite know what she would do next in any given situation. He still wasn't sure what she did or didn't know about him and what she was planning to do with whatever information she had picked up about him. Killing her would have been a very stupid thing to have done. There was, he decided, as he turned over to address himself to sleep, quite a lot of mileage in her yet.