What a change today, what a mosaic of peoples, races, colours, languages, faiths, cultures the capital has become. Of its inhabitants at the 1981 census, more than one in six were born outside the UK - the breakdown was over a third of a million born in Europe, about 300,000 in Asia, around 170,000 in Africa and the Caribbean respectively, and lesser numbers from the other corners of the globe. All these different peoples have intermarried, with each other and with traditional Londoners.
This internationalisation provokes different responses. The British National Party foments race hatred and its thugs beat up Bengalis. Statesmen preach tolerance. Others are positively enthusiastic - massive immigration has given the metropolis just the vital spark it needed, bringing new life styles, foods, music.
However a lot of English-born whites, especially older people, find the cheek-by-jowl mixing of ethnic groups jarring and hard to accept. It wasn't like that when they were young; isn't such a new development a recipe for disaster?
The truth is it isn't new at all. London always was a city of foreigners. For much of its history the percentage of Londoners born outside the capital was actually far higher than today. In a remarkable book, A City Full of People (Methuen), the historian Peter Earle establishes that around 1700, when Samuel Pepys was an old man, Daniel Defoe in his prime and William Hogarth but a boy, a clear majority of Londoners had not been born in the capital. Many had come from overseas: Huguenots from France, Jews from Spain and Eastern Europe, Scandinavians and Germans, Moors and other Mediterranean types. And there are flocks of Welsh, Scots, Irish, and people from the ends of England. Cumbrians and Cornishmen might not seem 'foreigners' to us, but that's how they were perceived at the time, with their different ways and dialects: one sailor around 1700 told a court he spoke 'English and Devon'.
A hundred and fifty years later, under Queen Victoria, things were much the same. Between 1841 and 1851, a third of a million streamed into the capital, representing a staggering 17 per cent of London's total population. Similar numbers arrived in the 1850s and 1860s.
The majority of these came from a few ethnic groups. Nearly 50,000 arrived from Ireland in the 1840s alone, fleeing the famine. By 1850, London's Jewish population had increased to about 20,000, and in the following fifty years, as refugees deluged in from central Europe, Poland and Russia, it had leapt to 120,000.
The city always had pockets of more exotic sorts. By 1800 there were several thousand Black Africans, mostly servants and sailors but also a few musicians, prize-fighters, gigolos and writers. Lascar sailors settled from South East Asia, and from 1800 Limehouse was acquiring its Chinese community; the notorious opium dens came later.
This ceaseless flow of migration shouldn't surprise us for a second. After all, Londinium was founded by the Romans, conquered by Saxons and Normans and developed as a commercial centre by Italian, Flemish and Baltic traders. It was always a honeypot for potential Dick Whittingtons (he came from Gloucestershire).
If the streets were not paved with gold, the capital always had work, and wages were good. So people poured into what a rather jaundiced 18th-century commentator called 'that great and famous city, which may truly be said, like the Sea and the Gallows, to refuse none'. Without migrants London would never have been famous for silks and watches (made by French craftsmen); it would have lacked ice-cream (made by Italians living in Finsbury) to say nothing of the music of Handel.
True, by the lifetime of my neighbour, Mrs London, newcomers had grown much less
conspicuous, but that was just a lull; over the centuries the tide of migration has never stopped. And so today's fears of a multicultural capital are myopic, because that is exactly what London always was, during the centuries of greatness when it became the top city in the world.
What we need to fear is not the pot-pourri of peoples but the lack of the conditions that have enabled multiculturalism to thrive: jobs, homes, education, opportunities - all those elements that ensure integration into the wider community.
Over the centuries London has been pretty successful at avoiding serious racial tension and violence. There never was a formal Jewish
ghetto. The humiliation of the BNP in recent local government elections shows that old Cockney traditions of live-and-let-live remain strong. But tolerance will be stretched by continuing poverty and hopelessness.
Multiculturalism requires a metropolis where prosperity is a prospect for all. And that requires urgent action.
Roy Porter is professor at the Wellcome Institute for the History of Medicine