Text 4　　 　　London’s fastest-changing art gallery is hidden in a sunken ball court on a housing estate in Stockwell, South London. On a sunny Sunday afternoon six or seven men, mostly in their 30s, are busy painting the walls with new designs. They have put up cartoons, names written in elaborate, multicoloured lettering and clever perspective tricks. Tins of spray paint and beer stand on the ground; ladders lean against the paintings. The atmosphere is not unlike that of a golf course: a mix of concentration and relaxation. 　　Graffiti painting is traditionally a dared evil pursuit. Teenagers dodge security guards to put their names on trains and buses. But over the past decade that has all but disappeared from Britain’s cities. Between 2007 and 2017 the number of incidents of graffiti recorded by the British Transport Police fell by 63%. A survey by the environment ministry shows that fewer places are blighted by tags than ever. Graffiti are increasingly confined to sanctioned walls, such as the Stockwell ball courts. In time the practice may die out entirely. 　　The most obvious reason for the decline in tagging and train-painting is better policing, says Keegan Webb, who runs The London Vandal, a graffiti blog. Numerous TV cameras mean it is harder to get away with painting illegally. And punishments are more severe. Once-prolific taggers such as Daniel Halpin, who painted his pseudonym “Tox” all over London, have been given long prison sentences. British graffiti artists who want to paint trains usually go abroad to do it these days, says Mr Webb. 　　A generational shift is apparent, too. Fewer teenagers are getting into painting walls. They prefer to play with iPads and video games, reckons Boyd Hill, an artist known as Solo One, who in effect runs the Stockwell ball courts. Those who do get involved tend to prefer street art to graffiti proper (which purists define as letters and names, however elaborately drawn). Some have gone to art school and want to make money from their paintings. The internet means that painters can win far more attention by posting pictures online than they can by breaking into a railway yard. 　　Graffiti may eventually disappear. But for now the hobby is almost respectable. Mr Eine says he has lots of friends who used to paint trains. Now with wives and children, they paint abandoned warehouses at the weekend. It has become something to do on a Sunday afternoon—a slightly healthier alternative to sitting watching the football.