Perhaps his own Angel could sleep with another Angel with Aids. And then be tested twice, once while the infected Angel was still in the world, and again, once he had left it to see if the virus remained behind.

But that meant the slate would be cleaned whenever the carrying Angel disappeared. And even perhaps when his own experimental Angel dipped in and out of existence.

Both the infecting Angel and his victim would have to remain in the world for an uninterrupted three months.

Well, Michael could rent a house somewhere out of the way, Scotland maybe, and have them live there under iron orders to sleep with no one else. It was a little bit like keeping experimental dogs in kennels. There was no doubt that science was easier when you did it to animals.

But Angels are not people. What if their immune systems worked differently? Suppose Angels could infect people but not each other?

Michael considered testing with a less serious virus. He could conjure up an Angel with a severe cold, sleep with him, and see if he caught anything. Or call up a copy with diphtheria on his moustache and swab his own lips and grow a culture.

But HIV was a retrovirus. It copied itself into the RNA of your cells, and took over their reproductive function. It becomes you, and you are real. Suppose over the three months it worked its magic, the virus became so entwined with your non-miraculous body that it gained a real life?

The more he thought, the more difficult and absurd it all became.

Then he remembered that one of his many lost opportunities had grown up to be an expert on Aids. Her name was Margaret White, but Michael had known her in school as Bottles. They had been friends during Michael's brief period of popularity before his last trip to California.

At sixteen, Michael was just American enough to find it easier to meet strangers and stay sunny and positive about things. He was invited to parties. He was likely to succeed, and grumpy jealous spotty pale blokes grumbled about him behind his back.

Michael was in the school theatre club and was big and strong and handsome and could act. There were more girls in drama club than blokes, so they did a production of Anouilh's Antigone: lots of juicy female roles. Michael played the old, heart-torn tyrant. He moved with a combination of bullish swagger and slight arthritic limp that left the audience astonished. Michael had conjured up the king.

His sport was long-distance running. The beefiness he inherited from his father was yet to develop; he maintained an easy luxurious swing to the way he moved. He combined beauty with a certain shy sweetness that did not threaten or repel, and his black eyes reminded people of a particularly friendly, lively spaniel. Indeed, he was very good with animals. He worked for the local vet part-time and had decided to become a veterinarian.

The nicest thing about Michael was that he was no snob.

Bottles was the unkind nickname given to a big-breasted girl who existed on the social margins. She was tall, big-boned, a little ungainly, with a certain daffy spinning to her eyes. Her classmates whispered about her with a fascinated prurience, because at sixteen, Bottles was living the life of grown woman. She looked 22, had adult boyfriends with cars, and spent weekends in clubs. Rumour was accepted as fact: Bottles did a strip show in the local pub.

Michael got to know Bottles on a school trip to Windsor Castle, an attempt to steep them in the mystique of royalty. They met over a joke.

As they got off the train at one of Windsor 's stations, Bottles said to him, cheerily, 'My goodness, two train stations. Is that so the Queen can get away in case there's a revolution?'

It was 1976 and there was little to make any hungry secondary-scholar feel wild, free and funny. Bottle's top was cut low, and her breasts were squashed together, showing pale skin and a hint of blue veins. She had been sent home recently for the unheard-of thing of piercing her nostril with an earring.

'I mean, do you suppose the Queen goes to the toilet in public? I'm being serious. There she is, waving to crowds and suddenly she gets caught short. Can she say, sorry everyone, I need a pit stop? Or does she just have to wait until she gets home?'

To a sixteen-year-old in the run-up to the Jubilee, this was scandalously original. Bottles began to walk in a clenched, constricted way and grunted in agony. 'One is so pleased to be hyah.'

Michael laughed, partly with disbelief that someone real could suddenly start saying such things. He laughed with relief because he found Bottles reassuring. Daftness is not only funny but very slightly pitiable.

Michael's laughter was constrained by fear, fear of being awkward or saying too much, and this constraint made it elegant. It was elegance that Bottles craved.

Both of them felt an irresistible tug of charm. Bottles suddenly put her arm through his.

'You,' Bottles announced, 'are a Louise.'

Michael's panic surfaced: how did she know? Had someone told her? If someone had told Bottles then maybe everybody knew.

She saw it and chuckled. 'Don't look so baffled,' she said, and stroked the top of his brown and flawless hand. 'Louise is a club. It's run by the most wonderful Frenchwoman and she's called Louise and so her club is too.' She lapsed into fake American. 'You wanna go?'

Michael beamed relief and friendship. 'Absolutely, without fail, please.' After all, he was the school's official American, and Americans are never supposed to be afraid.

She got the message. He liked her. 'Friday night OK with you?'

Michael offered, 'Or Saturday, Sunday, Monday, Tuesday

'Full social calendar, huh?'

'I'm a hot date, but I can squeeze you in.' Michael felt sophisticated, all of 22. 'I'm generally pretty busy except for weekdays and weekends.'

'Aw,' she said and gave his hand a quick squeeze. 'And you're the nicest man in the year.'

At sixteen there is something irresistible about being called * a man, especially by someone who has had some experience of them. And with whom, for some reason, you feel both safe and giddy at the same time.

So that Friday they went to the Club Louise in Soho.

Michael loved it. It was full of other daffy people, starting with Louise herself. She sat in a basement cubbyhole, greeting teenage visitors from Bromley as if they were French aristocrats. She took Bottle's coat (long with a collar of black feathers that smelled of burnt sesame oil), and kissed her on both cheeks, and called her 'ma cherie' with a skeletal detachment.

Bottles looked a cool 25 let alone sixteen. She ordered champagne. A woman called Tami bubbled up to them, nipping someone else's glass off a table en route. She held it up, empty, with a hungry grin. Tami wore black gloves with rings on the outside, something so chic it made Michael speechless with admiration.

Tami talked about American black music, how only American black music was worth listening to. Did he see Bowie at Wembley? Amazing, all done with just those brilliant white lights, everything black and white, and he just strolled out of this haze of light. 'I got so excited, I nearly mussed my perm.'

Michael loved Station to Station. Drunk, emboldened by moral support, he went up to the DJ's hidden booth and asked for his favourite track, 'TVC15'. Instead of curling his lip in contempt as Michael expected, the DJ said, 'Too right, mate.'

So up came 'TVC15', and Michael, out of sheer love, began to dance. This should have been terribly uncool. No one else was dancing.

But Michael was grinning like a monkey, and he had decided at the last minute to rent a tuxedo, onto which Bottles had pinned her earrings. Somehow that was just right. Suddenly, with an ungainly whoop, Bottles and most especially Tami joined him. That probably did it. An awful lot of people looking tough at tables were suddenly left behind as people started to dance.