Dinner with a couple who are in town for a week. Then with another. Each pair, unknown to the other, expresses an itch to move to London. Each testifies that it is more “cosmopolitan” than their present habitat. No news there. A common report.

Now, if I tell you that one of the couples lives in Paris and the other in New York, you might perk up a bit. No one, after all, walks round those two cities and bemoans a lack of human diversity.

And that is the point of this column. Being diverse is not the same as being cosmopolitan. One is a material fact: this many ethnicities in a place, this many languages spoken, this many religions professed. The other is — what? — a mental state. Defining it is hard but here is my best shot: knowing about the world, and not much caring. It is a sort of informed indifference. Some people fall down on the first point. However well they mean, their experience is narrow. Others flunk the second test. Their focus on ethnic or other group identities can be draining and even dehumanising to be around.

Fail on both counts and you are, well, you are “woke”, aren’t you? My grievance with that movement isn’t the statue-felling and the person-cancelling. Most ideologies are intolerant. Having seen tabloids attempt to intimidate judges, I wouldn’t sooner trust conservatives with cultural power. No, what grates is something else. They’re so provincial. So hazy about the non-western world they pretend to bat for. The ignorance manifests as treating “Africa” as though it were a state, empire as something European, and all non-white people as more or less on the same side.

They are expert diversifiers and hopeless cosmopolitans. It is why, when lots of Hispanic voters went Republican, and Asian students petitioned against affirmative action, the cultural left couldn’t see it coming. A worldlier lot would have known that “people of colour” is not a coherent bloc. (Let me tell you about a place called Sri Lanka.)

If a city can be diverse while not being cosmopolitan, can it be cosmopolitan while not being diverse? Jan Morris, the great travel writer, might have put in a word for Trieste or Venice at various points in their histories. Above all, to qualify as cosmopolitan, a place has to be multicultural, I think, not just multi-ethnic. A melting pot is a noble thing. So is assimilation under the French republic.

But neither suggests a nonchalance about difference. No, that takes a special degree of self-esteem in the host territory to pull off. The unspoken statement is, “The essence of this place can survive all change”.

Eighteen Julys ago, terrorists set off lethal bombs around my city, killing 52 people. By way of response, the then mayor told those who supported the murderers’ cause to watch our airports, seaports and international train terminal in the subsequent days. People from all over would still come in their droves, he said, because London allows them — how the words have stuck — “to be themselves”.

Telling phrase, isn’t it? He might have said “to become British”. Or “to improve their lives”. Or some such. And look, you can do those things. I had done both by then. (I am a mediocre cosmopolitan. Much too grounded in one place.)

Instead, what he dwelt on was the absence of pressure, not just from the state but from other citizens, to be like this or like that. It can verge on nihilism, this live-and-let-live code. It is what Joseph Conrad is getting at in The Secret Agent. But having been back for a year, I recognise it as the distinct achievement, even the point, of London.

And while some of the same spirit permeates Dubai, Toronto and Bangkok, I don’t expect another city to match this cultural looseness in my lifetime, resting as it does on things that can’t be magicked up just anywhere: centuries of habit, geographic location, the English reverence for the private realm and ultimate confidence in the law as the one binding agent. West London in particular, for all my gripes about its erratic taste, is masterly at this. There might be some slab of Earth more replete with and yet more insouciant about national differences, but fortune hasn’t taken me there.

“Defend diversity”, said a sign held up at a protest last week at the US Supreme Court ruling against positive discrimination. Well, I suppose. But diversity is learnable. Look at Germany two generations ago and Germany now. Look at several of the highest office-holders in the UK. Japan is loosening up on immigration. Cosmopolitanism, even trickier to achieve than it is to define, is the real feat