LONDON  Every week without fail Lucy Elkin, a comfortably middle-class mother of two small children, receives a £33.20 child benefit payment, or about $52, from the debt-plagued British government.

“It’s useful and it helps pay the bills, but it is not as if we are struggling to put food on the table,” Ms. Elkin said as she led her children from the park to their house on the leafy fringe of Hampstead Heath, one of London’s most desirable neighborhoods.

Ms. Elkin, 40, is a freelance writer. Her husband is a computer programmer. Along with more than three million middle- to upper-income British families, they are among the recipients of £11 billion ($17.2 billion) a year paid to mothers with children here. It is a universal benefit that not only costs taxpayers about twice as much as the total for unemployment payments but also represents the largest chunk of the estimated £30 billion ($47 billion) the government pays each year to Britons with above-average incomes.

“It is one of those things that is quite hard to justify,” Ms. Elkin said.

She is not alone in thinking that Britain can no longer afford such generosities. But even as civil servants and ministers are preparing to drastically cut most categories of government spending to help close Britain’s budget deficit, the government is so worried about alienating middle-class voters that it is proceeding very cautiously in limiting the subsidy for having children.