Tourists are snootily derided by the very London-dwellers who are forever bothering the poor foreigner with their polished diffidence in Provence, Tuscany or the Caribbean. These gripers are the very people who expect to be accepted as special abroad. In fact the word 'tourist' is a cold, complacent insult. We're all tourists. We're all on a lease.
In some languages, 'stranger', 'foreigner' and 'guest' are the same word. The poorer the nation, the longer the national anthem and the warmer the welcome to strangers, who bring luck, the chance to give something.
It is true herds, gaggles or schools of tourists can be what we in Britain call a nuisance, a moving, amoeboid, lurching, jellyfish-like microsociety, collectively clingy.
Crocodiles of Euro-youth cross the road as one inseparable being. The kids believe they have right of way, that you can disrupt the traffic in London and it's cool. That in insular England you can be cheeky, naughty, slightly rebellious, endearingly eccentric, without getting into trouble. They believe you could probably borrow a policeman's helmet and all the bobby would do is say: 'Now then sonny, tut tut.' They may even think that our policeman have rugby ball-shaped heads which is why their helmets are so funny.
So much of British life is so inexplicable. Worldwide, English people are widely regarded as mad. So visitors expect a lot from London, England. They expect it to be swinging. They expect a certain kind of whimsy from the English, the kind of friendly cheek represented by the Beatles from Liverpool.
Ray Davies of the Kinks had the tone of London brilliantly in his songs. Waterloo sunset. What are we living for, two-room apartment, second floor. The taxman's taken all my dough, left me in my stately home. The picture is partly of a stately architecture, lush lawns, a yellow Rolls Royce parked, and people behaving inexplicably.
So maybe the groups are a nuisance but, individually, people from away staying here should be able to expect a certain humour, good humour, from London, not just grandeur and pomp. The 1980s have shaved the humour off a lot of London life.
Last week there was a man in the underpass maze of Marble Arch shouting out instructions to tourists baffled by the hieroglyphics: 'Tube straight ahead, Oxford Street first right.'
He was, in fact American, maybe 60, with Buffalo Bill moustache, hair and air. For him, xenophobia was simply alien.