It is historically Paris, not London, that has lived by numbers - Parisians have their 20 arrondissements and their systematic house numbering, while London has tangled boroughs and a riot of house names and numbers. There is a new class of Londoners, however, who navigate numerically. They live at 419 and work at 36. They meet friends at the end of 2, or lovers by 77. London's unofficial new geography derives from its buses.
I have been making a BBC2 documentary with Chinese immigrants brought to London by people smugglers, and they all use this method to find their way around.
English is as difficult for Chinese people as Chinese is for the English, and none of the new arrivals I met could speak more than a few words. This doesn't prevent them from selling goods, usually pirate DVDs, on the streets (this has largely displaced farm work), but they still have to get from A to B.
Place names are no use. Hackney is a mere guttural exhalation, indistinguishable from Hampstead. The points of the compass are no better, and they never, ever enter the linguistic labyrinth of the Underground.
Buses are their northern star: they need only identify which Mandarin characters correspond to 0 to 9 and the message displayed above the bus driver begins to make sense. When a new arrival is first taken by a contact to the flat he will share with a dozen others he is told the number of the nearest bus route. When he is taken to the gangmaster who will supply his DVDs he will memorise the bus number and the look of the streets that link bus stop to destination. One thing he must be careful about is the direction a bus is travelling in, and for this his best guide can be trial and error. If he travels for a long time without seeing things he knows, he must alight and try the other direction. In this way most new immigrants build up a repertoire of routes.
When they talked to us, many identified locations that could easily be given names using a bus map and an A-Z. Most had been mugged by British teenagers who know they carry DVDs and can't tell
the police. The site of an attack might be "the place five stops along the 149 from home, then three streets to the right".
It can go wrong. One man arrived an hour late to meet us: he thought he knew how to get from the bus stop to our meeting point, but didn't. To find his bearings he had no option but to keep walking in a random direction until he saw a bus stop with a number he knew. That day all his frustrations about life here - the risk of attack and arrest, the stress of earning enough - poured out. Discarding inscrutability and every other ethnic cliche, he stood in Whitechapel (seventh stop on the 393, two streets on the right) and cried his eyes out.
The second episode of Chinatown is broadcast on BBC2 on Tuesday 31 January at 7pm