"It's like I'm sliding sideways through time and space," Quentin explained.

Vivienne nodded encouragingly.

"You might have seen that movie Sliding Doors with Gwyneth Paltrow," he continued. "Maybe, in this continuum, it stars Renee Zellweger."

"I'm sure it was Uma Thurman."

"Whoever." Quentin took another sip from his beer. "Sliding sideways, she was. Only for me, it's happening all the time."

"All the time?" Vivienne asked, raising an eyebrow. "How can that be?"

"It's like Stephen Hawkings explains. You know, that we live in an infinity of parallel universes. Only that while most people stay in one spacetime continuum all their lives, I'm constantly sliding through all of them. I don't go backwards and forwards in time. I just go forwards, but the universe I'm in changes around me. And I've got no control of it any more than most people have any choice about which parallel universe they spend the whole of their lives in."

Quentin paused to assess Vivienne's reaction. Was she humouring him? He often felt the urge to confess his predicament. He knew that the Quentin who would live with the confession was the Quentin whose body he was currently occupying and who would, no doubt, be thoroughly confused by the memory of this occasion.

Vivienne tapped her cigarette on the ashtray. "Go on," she urged him.

"Are you sure?" Quentin asked.

Most women he spoke to on this matter would now ask "What you on?" Or they would pretend not to have heard anything. He was more anxious than he should be. Why should he care what Vivienne thought about the Quentin she had just met? Not all Quentins were especially kind to him for the moment of his residency. He had several times suffered venereal disease, war wounds, and an uncomfortably generous waistline.

"Yes. It's fascinating," said Vivienne, puffing smoke from her cigarette and running a long fingernail along the rim of her wine glass.

"I've seen so many different worlds," Quentin continued. "There are those where the Cold War persisted with the Soviet Union under President Andropov until the present day. There are those where President Kennedy was not assassinated at Houston. There are those where the Sex Pistols never existed. There's even one where some Arab terrorists flew Boeing 747s into the World Trade Center."

Vivienne raised her eyebrows. "I can't believe that! It's like imagining that Sir John Lennon never became the world's best selling novelist."

"I've seen that. He was assassinated, in fact," Quentin admitted. "I've even been in a universe where the richest man in the world was that geek who runs Microsoft."

"I can't believe that either! How could IBM, Sun or Lotus allow that to happen?"

"It's like everything since the time I was born in the early 1960s that could happen has happened. Everything before then is the same in all the universes I've inhabited, but after that it sort of diverges."

"No nuclear wars?"

"Not ones I've survived, though there was a small one in the Middle East in the 1970s that led to universal disarmament. It's amazing what difference a few radioactive craters can make to a world!"

"I can imagine!" Vivienne said.

There was a curious sparkle in her eyes that suggested to Quentin that she was genuinely fascinated. She showed none of the amused scepticism that usually accompanied the most sympathetic ears to his predicament. Was she simply very good at hiding her real thoughts? Or was she playing him along?

"I once decided to write an account of my life," Quentin continued. "I had this 4GHz computer running this operating system called Winix. It was fantastic! And this was a few years back, whereas the best computers hereabouts aren't a quarter as fast. Anyway, I wrote all day and all night, while the wife I had, a pretty woman I've not seen since, kept moaning about me staying up. Then I thought I'd review what I'd written. And you know what?"

"What?" wondered Vivienne, raising her eyebrows in apparent interest.

"I didn't recognise what I read at the start of my account. It was like someone else had written it with totally different memories. It was then it occurred to me that there is a sort of continuum of Quentins, just like me, also sliding sideways through space and time. In fact, maybe everyone has a host of selves like me, perhaps an infinity of them in the infinity of parallel universes. And maybe people like me are everywhere."

"Fascinating!" remarked Vivienne, stubbing out her cigarette.

Quentin scrutinised Vivienne closely. Despite her apparent encouragement, Quentin was still half-expecting a sarcastic rejoinder. Did she really believe him? She was an attractive woman, who carried around with her a self-assurance that would normally manifest itself in contempt towards a man like him, any man, who told a story that must seem ridiculously far-fetched.

"You think I'm mad, don't you?" he asked her, as she brushed her black shoulder length hair off the sharp shoulders of her Giuseppe Marconi suit.

"Not at all," Vivienne said with a smile. "In fact, I think I might be falling in love with you."

"Now, you are taking the piss!" remarked Quentin.

How likely was that? He wasn't a bad-looking bloke and the Quentin he was now had reasonable dress sense with well-groomed hair and an expensive Ben Jones leather jacket. But no one had ever said that to him before after such a short time. And certainly not after he had divulged his most intimate truths.

Vivienne shook her head. "I'm not taking the piss, Quentin. Although it's a bit of an exaggeration to say I'm in love as such, you are just the man I've always wanted to meet. All my life, in fact."

Quentin blushed. "I simply don't believe that..."

"You're right. You're not the only one 'sliding sideways' through space and time, as you call it. It's my life as well, you know, although I don't have a term for it. It's just I've never met anyone the same as me in that way."

Quentin shook his head violently and squeezed his eyes tight. When he opened them, Vivienne was still there.

"You mean you're like me? Every day you wake up and live in a slightly different world, subtly changing and mutating?"

Vivienne nodded. She opened her cigarette packet and put another Marlboro Gold Tip in her mouth.

"It's not always gradual. That's why I asked about nuclear war. I spent a whole week in a kind of post-apocalyptic world. It was horrible! I had to eat rats and wear a lead-lined coat. That Ronald Reagan went just a little too far with his threats against the Soviets in the Pakistani missile crisis..."

"I remember that. It was touch and go, as far as I remember."

"And then President Brezhnev, the senile git, called Reagan's bluff and it was fireworks! I wasn't there for the crisis, but I was there several years later. The thing is it happened suddenly. One moment I was living in this student squat in Hackney, the next minute in some nuclear wasteland. And when I came out of it, that was sudden as well. I was walking through some woodland trying to avoid some thuggish scavengers, and when I emerged at the end, it was by a motorway, only instead of it being empty and overgrown with mutant grass, there were cars driving along it, just like there'd never been a nuclear war. As I guess there never had been. I was fucking delighted, I can tell you!"

Quentin shook his head again. "And I thought the Cuban Crisis might have become the big one!" he exclaimed.

"I've never met anyone else who knows what it's like, not so much living in a nuclear wasteland, but living each day in a different world. I thought I was the only one."

"So did I!" admitted Quentin.

At last! After all these years, here was proof that there were others who knew what he knew and lived the life he lived.

"So, how did you first discover things were like that?" Quentin asked. "I was in my teens. There are so many changes as you grow up, you don't realise that some are not the kind of changes that happen to everyone. You know, milk teeth falling out, your shape changing as you grow older, puberty, all that stuff."

"I think it was in my teens, too."

"When I tried telling people they thought I was mad. I was even taken to see a psychiatrist. But I discovered that pretty soon after I told people, they forgot about it. Other people, my parents, my friends, my teachers, didn't have the same memories as me. Eventually, I realised that it was the Quentin I'd been before and made the confessions who'd have to live with the consequences of it, not me. It was like I could start afresh every day. I discovered I could do whatever I fucking liked and I'd never need worry about living with more than the memory of it."

"Me too!" exclaimed Vivienne, drawing on her cigarette. "It's so fucking liberating! In fact, I've several times done things, just because I knew I could. I stripped naked in a pub. Just because I could. I sucked a stranger's cock in public because I knew I wouldn't suffer for it. I've had sex with anyone I fancied."

Quentin raised his eyebrows. "Well..." he remarked, "I've been a bit bolder than I might have been. Like I've been tonight, you know, approaching an attractive woman like you knowing that if you rejected me it'd be the Quentin I'm inside now who'd live with the rejection. I've been unfaithful to the several different wives and girlfriends I've had, who, after all, I didn't really know very well and didn't always like. I've often done things I can't claim to be proud of. No Groundhog Day redemption for me, I'm afraid. But I've never been as bold as you."

Vivienne shrugged. "I guess us spacetime travellers all have different ways of coping with the freedom we've been granted," she mused. "The Viviennes whose bodies I've occupied have all been pretty different: all the different ways I could have been, and, of course, somewhere in space and time actually am. Some Viviennes I've been were pretty tight-arsed and that's when I've probably been most wicked. The current Vivienne's got a boyfriend who works in the City, but she seems pretty free and easy. Which suits me! None of that 'Christ, Viv! What's got into you?' that I've heard so many times."

Quentin finished his glass of beer and pulled out a twenty pound note, with its head of King Charles the Third on the back, and waved it at the barmaid. "What do you want?"

"I'll have another glass of house dry white," Vivienne said.

"And I'll have another pint of Blackwell's. I've never heard of that beer before this week, but it seems to be the most popular round here."

"It's the little things that are most confusing," Vivienne commented. "I was amazed to see that there's no Jubilee Line here. And no one's ever heard of Madonna. She never made it big in this world. And who'd believe that Colin Powell would become President of the United States!"

The two of them threaded through the crowded bar to some seats by the jukebox on which was playing a selection of old pop songs, some familiar, some surreally different in detail and some totally unfamiliar. Quentin studied Vivienne with an approving eye as they sat down.

She was a little younger than him, probably in her mid to late thirties. She was a woman who, being so slender and assertively pretty now, must have been quite a head-turner when she was younger. She crossed her long slender legs, almost all her stockinged thigh on display under her fashionably short skirt, and her blouse coquettishly unbuttoned under her smart jacket.

Vivienne smiled. She flashed a healthy dental display behind her wide reddened lips. She pulled out another cigarette from her packet and lit it.

"I still can't believe it's true!" she said, unable to disguise the excitement in her voice.

"So, where do you live and what do you do?" wondered Quentin. A fairly obvious question really, but he knew the answer wouldn't be so obvious.