Over the past decade, public targets of crackdowns have shifted from “bogus asylum-seekers” to “criminal aliens” and now to “unsustainable net immigration,” a term that includes perfectly legal settlers, noted Mary Bosworth, a criminologist at the University of Oxford who has tracked the expansion of immigration jails like Yarl’s Wood.

“There is this very public display and investment in making these places of confinement look like they’re holding dangerous people,” Ms. Bosworth said. “It locks the government into the position where it can only get tougher.”

And the rules keep changing. Last year Antonio passed a new “Britishness test” — What is a shadow cabinet? When is Mothering Sunday? — only to learn that it no longer counts in his case.

“Great for a pub quiz, though,” he said.

A Family on the Run

At first, the Bravos were a family of four: Mr. Bravo, calm and quiet; his spirited wife, Lidia; their son, Nelio, 3; and Mr. Bravo’s son, Antonio, 10, whose own mother died giving birth to him in Angola. In asylum papers, Mr. Bravo described himself as a farmer jailed and abused by the Angolan government because of his role in a pro-democracy party founded by his father. He fled for his life, he said, after security forces raided the family farm and killed his parents and sisters. Angola was then in the 27th year of a civil war.

The Bravos requested asylum when they landed at Heathrow Airport in October 2001. Barred from work like most asylum-seekers in Britain, they were sent to Armley to await a decision. They found support at Christ Church from Catherine Beaumont, a volunteer at its immigrant help center, and the Rev. Alistair Kaye, then the vicar.

But their application had joined a backlog just as the number of new asylum-seekers in Britain soared toward a peak of 84,000 a year in 2002. Public hostility soared, too, over revelations that few of those denied asylum ever left.

The detention center, Yarl’s Wood, was then just opening, part of an expansion that the government and its private partners promised would triple the rate of expulsion. Instead, within three months, the $140 million center was gutted by fire during detainee protests over mistreatment.