Some other girls from the stall gathered round to help, but they were also defeated by our picture. At last I plucked up the bravado to perform a delicate little mime and at last the penny dropped.

'Ah!' the first girl said, suddenly wreathed in smiles. 'Ah yes!'

They all beamed delightedly at us as they got the idea.

'You do understand? l asked.

`Yes! Yes, I understand.'

'Do you have any?

'No,' she said. 'Not have.'

'Oh.'

'But, but, but...'

'Yes?

'I say you where you go, OK?

'Thank you very much. Thank you.'

'You go 616 Nanjing Road. OK. Have there. You ask "rubberover". OK?

`Rubberover?

'Rubberover. You ask. They have. OK. Have nice day.' She giggled happily about this with her hand over her mouth.

We thanked them again, profusely, and left with much waving and smiling. The news seemed to have spread very quickly around the store, and everybody waved at us. They seemed terribly pleased to have been asked.

When we reached 616 Nanjing Road, which turned out to be another, smaller department store, and not a knocking shop as we had been half-suspecting, our pronunciation of 'rubberover' seemed to let us down and produce another wave of baffled incomprehension.

This time I went straight for the mime that had served us so well before, and it seemed to do the trick at once. The shop assistant, a slightly more middle-aged lady with severe hair, marched straight to a cabinet of drawers, brought us back a packet and placed it triumphantly on the counter in front of us.

Success, we thought, opened the packet and found it to contain a bubble sheet of pills.

'Right idea,' said Mark, with a sigh. 'Wrong method.'

We were quickly floundering again as we tried to explain to the now slightly affronted lady that it wasn't precisely what we were after. By this time a crowd of about fifteen onlookers had gathered round us, some of whom, I was convinced, had followed us all the way from the Friendship Store.

One of the things that you quickly discover in China, is that we are all at the zoo. If you stand still for a minute, people will gather round and stare at you. The unnerving thing is that they don't stare intently or inquisitively, they just stand there, often right in front of you, and watch you as blankly as if you were a dogfood commercial.

At last one young and pasty-faced man with glasses pushed through the crowd and said he spoke a little English and could he help?

We thanked him and said, yes, we wanted to buy some condoms, some rubberovers, and we would be very grateful if he could explain that for us.

He looked puzzled, picked up the rejected packet lying on the counter in front of the affronted shop assistant and said, 'Not want rubberover. This better.'

`No,' Mark said. `We definitely want rubberover, not pills.'

`Why want rubberover? Pill better.'

`You tell him,' said Mark.

'It's to record dolphins,' I said. 'Or not the actual dolphins in fact. What we want to record is the noise in the Yangtze that... it's to go over the microphone, you see, and...'

'Oh, just tell him you want to fuck someone,' muttered Chris, scottishly. 'And you can't wait.'

But by now the young man was edging nervously away from us, suddenly realising that we were dangerously insane, and should simply be humoured and escaped from. He said something hurriedly to the shop assistant and backed away into the crowd.

The shop assistant shrugged, scooped up the pills, opened another drawer and pulled out a packet of condoms.

We bought nine, just to be on the safe side.

'They've got aftershave as well,' said Mark, 'if you're running out.'

I had already managed to dispose of one bottle of aftershave in the hotel in Beijing, and I hid another under the seat of the train to Nanjing.

'You know what you're doing?' said Mark as he spotted me. I'd thought he was asleep.

'Yes. I'm trying to get rid of this bloody stuff. I wish I'd never bought it.'

'No, it's more than that. When an animal strays into new territory, where it doesn't feel at home, it marks its passage with scent, just to lay claim. You remember the ring-tailed lemurs in Madagascar? They've got scent glands in their wrists. They rub their tails between their wrists and then wave their tails in the air to spread the scent around, just to occupy the territory. That's why dogs pee against lampposts as well. You're just scent-marking your way round China. Old habits die hard.'

'Does anyone happen to know,' asked Chris, who had been lolling sleepily against the window for an hour or so, 'what the Chinese for Nanjing actually looks like? I only ask so as we'll know when we've got there.'

At Nanjing we had our first sight of the river. Although Shanghai is known as the gateway to the Yangtze, it isn't actually on it, but is on a connecting river called the Huangpu. Nanjing is on the Yangtze itself.

It is a grim town, or at least we found it to be so. The sense of alien dislocation gathered us more tightly into its grip. The people we found to be utterly opaque, and would either stare at us or ignore us. I was reminded of a conversation I had had with a Frenchman on the plane to Beijing.

'It is difficult to talk to the Chinese people,' he had said. 'Partly it is the language, if you do not speak Chinese, but also, you know, they have been through many, many things. So they think it is safer perhaps to ignore you. If they talk to you or do not talk to you they are paid the same whatever, so, pfffft.

'I think if they get to know you they talk a little more, perhaps, but pfffft.'

The sense of dislocation was sharpened by the presence, in the centre of town, of a single major Western-style high-rise hotel, called the Jing Ling. It was an anonymously grand conference-holding, revolving-bar-and-atrium-ridden modern hotel of the sort that generally I heartily dislike, but suddenly it was like an oasis to us.

We made straight for the revolving top-floor bar like rats from a sack and sat huddled for safety round a cluster of gin and tonics. After twenty minutes or so of sitting in these unexpectedly familiar surroundings, we found, as we gazed out of the panoramic windows at the vast, alien, darkened city which turned slowly around us, that we felt like astronauts in a vast, warm life-support system, looking out over the hostile and barren terrain of another planet.

We were all seized with a sudden desire not to have to go out there any more, not to have to be stared at, ignored, spat at, or have our personal space invaded by bicycles. Unfortunately the Jing ling had no free rooms, and we were ejected into the night to find lodging in an altogether grimmer crumbling hotel on the outskirts, where we sat and thought, once more, about the dolphins out in their filthy river and how we were to make our recording.

On a day darkened with drizzle we stood on' the bank of Yangtze, watching the great drifting sea of sludge which flows sullenly from the depths of China. The only colour in a heavy landscape of dark brown shading to grey, against which long, black, smoke-belching silhouettes of diesel-engined junks thudded and growled up the river, was a little pink knotted condom dangling limply on the end of a cable attached to Chris's tape recorder. The half-heard swish of unseen multitudes of bicycles was like the distant drumming of hooves. From here the bewilderment of Shanghai seemed like a remote warm memory of home.

The river was not deep enough at the bank for our sound experiment, and we slogged our way through the accumulating rain towards the docks in search of deeper water. We shook our heads at the occasional importunate cries from passing bicycle-driven rickshaws, being too sunk in gloom to admit even the possibility of relief.

We found a temporarily deserted passenger ferry lolling against the creaking dock and trudged up the gangplank. The ferries are big, hulking, five-decker wedges, which look like immense, soiled slices of lemon gateau grinding daily up and down the Yangtze, each carrying upwards of a thousand cramped passengers and playing Richard Clayderman at them. We found our way through a series of bulkhead doors to a deck which overlooked the river, where Chris tried hopelessly to dangle the little pink thing with its button microphone down into the murky waters. It would scarcely reach, was blown about by the wind, and when at last it dropped down to the water it sat perkily on top of it.