'Make up your own past life?' Sceptically.

'Some people do it all the time.' I think I am teasing, but even as I speak the words, I wonder.

'Only to fool other people. They must know they're lying.'

'I'm not sure it's that simple. I think the easiest people to fool are ourselves. Fooling ourselves may even be a necessary precondition for fooling others.'

'Oh no,' she says quite definitely. 'To be a good liar you have to have a very good memory; to fool others you usually have to be cleverer than they.'

'You think no one ever believes their own stories?'

'Oh, maybe a few people in psychiatric hospitals do, but that's all. I think most of the patients who claim to believe they're other people are just playing a sort of game with the staff.'

Such certainty! I seem to recall being that sure of things, even if I can't remember what it was I was so definite about. 'You must think doctors very easy to fool,' I say. She smiles. Her teeth are unobjectionable. I am aware of evaluating this young woman, of sizing her up. She is entertaining without being entrancing, absorbing without being captivating. Probably just as well. She nods.

'I think they can be fooled quite easily when they treat the mind like a muscle. It doesn't seem to occur to them that their patients might be trying to fool them deliberately.'

I'd dispute this: Dr Joyce, for one, seems to make it a matter of professional pride never fully to believe anything his patients tell him. 'Well,' I say, 'I think a good doctor will usually spot the charlatan patient. Most people lack the imagination to assume the role sufficiently well.'

Her brows crease. 'Maybe,' she says, staring past me intently, unfocused. 'I'm just thinking of childhood, when we -'

At this point, the young man sitting on the far side of her, with his arms on the table and his head on his arms, stirs, sits up and yawns, looking round with bleary eyes. Abberlaine Arrol turns to him. 'Ah, awake once more,' she says to him, a gangly fellow with close-set eyes and a long nose. 'Finally scrape together a quorum of neurons, did we?'

'Don't be a shit, Abby,' he says after a dismissive glance at me. 'Get me some water.'

'You may be an animal, brother dear,' she says, 'but I am not your keeper.'

He looks about the table, which is mostly covered in dirty plates and empty glasses. Abberlaine Arrol looks at me. 'I don't suppose you know if you have any brothers, do you?'

'Not to the best of my knowledge.'

'Hmm.' She gets up and heads for the bar. The fellow closes his eyes and leans back in his seat, making it swing slightly. The bar is emptying. Only a few legs can be seen poking out from beneath distant tables, witnessing where their owners' alcoholic excursions into the long-lost days of four-limbed locomotion have come to their stupefied conclusions. Abberlaine Arrol returns with a pitcher of water. She is smoking a long, thin cigar. She stands in front of the young man and pours a little over his head, puffing on the cigar.

He stumbles to the floor, cursing, and stands up shakily. She hands him the pitcher and he drinks. She watches him with a sort of amused contempt.

'Did you see the famous aircraft this morning, Mr Orr?' Miss Arrol asks, watching her brother, not looking at me.

'Yes. Did you?'

She shakes her head. 'No. I was told about them, but I thought at first that it was a joke.'

'They looked real enough to me.'

Her brother finishes the water and throws the pitcher behind him with a theatrical gesture. It smashes on a table in the shadows. Abberlaine Arrol shakes her head. The young man yawns.

Tm tired. Let's go. Where's dad?'

'Gone to the club. But that was some time ago; he might be home by now.'

'Good. Come on.' He walks towards the stairs. Miss Arrol shrugs at me.

'I must go, Mr Orr.'

'That's all right.'

'Nice talking to you.'

'A mutual pleasure, then.'

She looks to where the young man is waiting, hands on hips, at the top of the steps. 'Perhaps,' she says to me, 'we'll have the chance to continue our conversation at a later date.'

'I hope so.'

She remains standing there for a moment; slim, slightly dishevelled, smoking her cigar, then executes a deep, mocking bow, hand flourished, and backs away, sticking her cigar in her mouth. A line of grey smoke curls after her.

The revellers have departed. Most of the people left in Dissy Pitton's are bar staff; they are switching out lights, wiping tables, sweeping the floor, lifting inebriated forms from the deck. I sit and finish my glass of wine; it is warm and bitter, but I hate to leave an unfinished glass.

Finally, I rise and tread the narrow corridor of remaining lights to the stairs. 'Sir!'

I turn; a broom-wielding barman is holding the wide-brimmed hat. 'Your hat,' he says, shaking it at me just in case I thought he meant the broom. I take the cursed thing, secure in the knowledge that had it been precious to me, had I been looking after it and trying to make sure that I didn't lose it, it would most assuredly have disappeared for ever.

At the door Tommy Bouch is being held against the wall by the no longer dormant doorman and quizzed on his identity and destination. Engineer Bouch seems unable to make any coherent noises, his face has a distinctly green hue about it and the doorman is having difficulty supporting him.

'You know this gentleman, sir?' the doorman asks. I shake my head.

'Never seen him before,' I say, then shove the hat between the doorman's arms. 'But he left his hat inside.'

'Oh, thank you sir,' the doorman says, he holds the hat in front of the engineer's face so that he can see it (or both of them, as the case may be). 'Look, sir, your hat.'

'Thanyoo,' Engineer Bouch succeeds in pronouncing, before transferring the contents of his stomach into the crown of the headgear. Thanks to the wide brim, of course, remarkably little splatters over the side.

I walk away feeling oddly triumphant. Perhaps that was what he wanted it for all the time.

'Not here?'

'Oh, golly, you know I really and honestly am sorry Mr Orr, but no, he isn't.'

'But I have -'

'An appointment, yes, I know Mr Orr. I have it here, see?'

'Well, what's the matter?'

'Urgent meeting of the Administrative Board Primary Subcommittee Vetting Committee, I'm afraid; pretty important. The doctor's a very busy man these days, sir. There are just so many calls on his time. You mustn't take it personally, Mr Orr.'

'I'm not -'

'It's just the way things go. Nobody likes all this admin stuff, but it's just a dirty job that has to be done.'

'Yes, I-'

'It could have happened during anybody's appointment; you were just unlucky.'

'I appreciate -'

'You mustn't take it personally. It was just one of those things.'

'Yes, of course -'

'And of course there's absolutely no connection with us forgetting to tell you we'd moved offices the other day. That was purely coincidence; it could have happened to absolutely anybody whatsoever. You were just unlucky. It really really isn't anything personal.'

'I-'

'You mustn't take it that way.'

'I'm not!'

'Oh, Mr Orr; not at home to Mr Tetchy, are we?'

Outside, remembering yesterday's eventful elevator journey, I head in the same direction as before, looking for the giant circular window and the entrance to the decrepit, L-shaped lift opposite it.

Increasingly frustrated and annoyed, I wander for over an hour through the high-ceilinged gloom of the upper structure, past the same blind-statued niches (ancient bureaucrats fastened in pale stone) and the same heavily hanging flags (furled like thickly ponderous sails on some great dark ship), but without finding the circular window, the old bearded man, or the lift. A senior clerk whose long-service ribbons proclaim he is a veteran of at least thirty years service, looks puzzled and shakes his head when I describe the lift and its grizzled operator.