LONDON — The tents have become a familiar sight on the streets of London, popping up outside stores shuttered by a slowdown in trade or even below the plate-glass windows of high-end home improvement outlets.

Small and flimsy, they offer some rudiment of shelter to the growing ranks of the homeless in a city that prides itself on the wealth of the banks and businesses that help make Britain’s economy the fifth largest in the world.

According to research made public on Thursday by a nonprofit organization called Shelter, the number of homeless people in Britain is increasing steadily and has reached at least 320,000 across England and Wales — an increase of 4 percent over the past year, despite a government drive announced in May supposed to keep people in their homes.

The figure includes people in temporary accommodation or hostels; Shelter puts the number of “rough sleepers,” the British term for those forced to sleep in the streets, at 5,096.