LONDON -- William Leithlaw didn't even notice that President Bush and the other leaders of the world's richest countries have swept into town this week to practice economics at the highest level.
He never reads the papers. He hasn't got a television set, or a room to watch it in.
Lounging in his blanket in a doorway on Chancery Lane, scratching his beard, Mr. Leithlaw was practicing economics at the lowest level: trying to figure out how he was going to make it through the rest of the week on what he had left of his $60 disability payment.
It's a struggle. Sixty dollars a week doesn't go far in London, and Mr. Leithlaw isn't much for budgeting. "I eat a little," he says. "I like to drink. Sometimes it lasts a week, sometimes a day."
This was a bad week. He expected to spend the night in the doorway -- if the polite woman in the leopard spot blouse who came out and asked him to leave did not insist -- or he would bed down outside St. Paul's Cathedral.
He has spent a good many of his 41 years drinking, defying the efforts of the temperance society in his hometown of Motherwell, Scotland, to rescue him.
He is a refugee from a psychiatric hospital and he has been on the streets for two years now. It shows. His eyes are like pits and signal a bottomless exhaustion. His teeth are rotting and the color of mud.
There is no telling how many homeless people there are in London. The most recent count was made by the University of Surrey for the Salvation Army and released in June.
In central London, a spokesperson at the Salvation Army said, "They found 2,000 people on the street, 18,000 in hostels, 25,000 in hotels, 30,000 in squats [collective encampments in empty buildings, under bridges, etc.], a total of 75,000."
Everybody agrees that a large proportion of them are young. Nick Carroll of the St. Mungo's Association, a national group that offers hostel beds to single homeless people, says, "Maybe 20 to 30 percent are young. A third to 40 percent come from broken homes. They aren't eligible for payments and are particularly vulnerable."
Since a change in the social security law here in 1988, youths under 18 are no longer eligible for the welfare benefits they once were; social security payments have also been cut back for those under 25.
Mark is 27 and falls into the category Mr. Carroll describes: He is alienated from his family, has been for the decade he's been on the street.
But unlike Mr. Leithlaw, he does have a faint appetite for current events. He knew something important was happening in London this week, but just wasn't sure what it was. Then he remembered.
"All those leaders coming here, Gorbachev and all them. Yeh, I know about it," he says, with a look on his face like that of a man who has just bitten into a bad egg. "I don't have naught to do with them," he says. "What has Bush got for me? Or Major?"
Of tax rates, trade and foreign debt Mark has no interest. His needs are more immediate, like where his next meal's coming from. But he's not desperate: Unlike Mr. Leithlaw, he still has the energy of his youth, and he figures he can keep body and wit together if he can panhandle about $14 a day. He eats cheese, eggs, soup.
"I'm a vegetarian, you see. I used to be a Marxist-Anarchist."
All you have to do to confirm the preponderance of youth among the street people is to walk through the downtown. They shiver in entryways to the Underground stations, young girls dress only in slips; you see them now and then being put into police vans.
They are rolled up in the doorways along the Strand like old newspapers, or huddled on the steps tumbling down through the narrow ways and tranquil gardens of the Inns of Court, where most of the city's lawyers have their offices.
Mr. Carroll estimates that there may be 40,000 people on the streets throughout Britain, which he admits is a low estimate. This does not count those in hostels or welfare hotels, but only the ones out on the hard bricks.
"Some people say there are as many as 3 million without a permanent residence in Britain," he said last week as he led about 500 young people to the House of Commons in an effort to lobby for relief for the homeless.
The story here is much the same as it is in the United States.
Many people blame the tough social policies of the former prime minister, Margaret Thatcher, for making a bad situation worse. The government says the conditions are the product of changes in family life -- more divorce and family breakup. In fact, Britain has the highest divorce rate in Europe, and more than double the number of illegitimate births of any European country except Denmark.
The government responded in late June with a plan to provide emergency shelters for people "sleeping rough." This is the preferred euphemism for being in the street.
"Sleeping rough" in London usually means sleeping in a cardboard box. The box is a symbol of homelessness. Mr. Carroll organized a National Sleep Out Week, which ended Sunday. He urged people to spend one night outside to dramatize the problem.
He got a lot of takers, including some famous ones. A group of actors and other people whose names are household words here camped out on the steps of Westminster Cathedral, a favorite haunt of the homeless. They hoped to draw attention to the crisis.
Instead they drew attention to themselves, got on television and in the papers, which drew a rough reaction from the real "rough sleepers." Feeling patronized, they denounced the dilettante vagrants. They objected most vigorously to the brand-new cardboard boxes the celebrities tucked themselves into, made especially for the occasion.
Ever since the G-7 leaders began arriving here over the weekend it has been hard to sleep in parts of central London, or move around in certain areas owing to the roar of the frequent motorcades and blocked-off areas. People of every class have been inconvenienced.
Yesterday morning as a motorcade roared by not far from Trafalgar Square, motors racing, horns blaring, a young vagrant started up from his nest in a doorway.
He glared dully at the speeding cars, scratched, then went back to sleep, plunging his head into his rolled-up jacket.