New Cross, where the Lengolos live, is not a neighborhood where you would expect to find great warmth for the queen. It is the source of some of London’s most influential music — reggae, ska, punk, and, more recently, grime — and of persistently high rates of violence.

Britain remains 87 percent white. Black people made up 3 percent of the population according to the most recent census, in 2011, many of them clustered in diaspora neighborhoods like New Cross. The racial tension goes back generations. In the 1970s, New Cross saw an influx of Caribbean workers invited to Britain for construction work. White immigrants bristled, and right-wing groups, like the National Front, began to march through the neighborhood.

Not far from Tshego’s house is a monument to racial division. In 1981, a house party on New Cross Road was engulfed in flames, leaving 13 young black men and women dead. Many people were convinced that racists had thrown a firebomb in the window, but a police inquest was inconclusive and no charges were brought. Thousands of black Londoners gathered in protest, the beginning of race riots that rippled through the city.

In New Cross today, the London of the global super-rich seems both tantalizingly close and unreachable. On a recent afternoon, uniformed police constables patrolled the park outside the high school, and young women in tank tops and eyelash extensions lingered in a playground, killing time. They were the grandchildren of Jamaican immigrants, and they said racism in Britain was getting worse.

Kemi Moore, 17, her hair marcelled like a 1920s movie star, said the 2016 campaign to leave the European Union had unleashed nativist feelings in white Britain. An immigration crackdown has swept up thousands of British-born descendants of the Caribbean workers — now known as the Windrush generation — who do not have citizenship documents, stripping them of health and housing benefits.