LONDON — It’s every parent’s nightmare: To get home from an event and realize that a child is missing. But it can turn out to be a political minefield as well if you happen to be the prime minister.
The incident sparked a debate in Britain about Mr. Cameron’s parenting and comes only a few weeks after the government set up a program to give parents of young children classes in how to raise them.
It also highlighted a sharp contrast with security procedures in the United States, where it is nearly inconceivable that a similar mistake would have been made with one of President Obama’s daughters. U.S. Secret Service agents routinely guard and monitor the president’s immediate family when they are out in public.
In Britain, it is common for people to see the prime minister shopping for groceries and other items on weekends, although it is difficult to tell if in fact he is being carefully watched by plainclothes agents.
Mr. Cameron’s office confirmed that there “are security arrangements in place for the prime minister’s family,” but declined to provide any details on the type of protection provided, or the numbers of detectives assigned to the leader’s wife and children.
“We do not comment on the prime minister’s security arrangements,” said a spokeswoman for Mr. Cameron, who spoke on customary condition of anonymity in line with policy.
She confirmed that no member of Mr. Cameron’s security detail had been judged to have made any mistakes in allowing Nancy to be left at the pub.
On the popular British parenting website Mumsnet, some people said the mistake was “easily done,” while others wondered why the Camerons had not kept a closer watch on their young daughter.
Downing Street said the incident happened “a couple of months ago” as the family was leaving the pub near Chequers, the official country house prime ministers use while in office.
Nancy had gone to the bathroom while Mr. Cameron and the rest of the family piled into two cars to drive back to the house west of London.
Mr. Cameron was traveling in one car with his bodyguards and assumed that Nancy was in the other car with his wife Samantha and their two other children. Samantha assumed Nancy was with her father, and they only realized she was missing when they got home.
The Cameron spokeswoman said “the prime minister and Samantha were distraught when they realized Nancy wasn’t with them. Thankfully when they phoned the pub, she was there safe and well.”
Nancy was separated from her parents for about 15 minutes until Mr. Cameron arrived to collect her from The Plough in the village of Cadsden, she added.
The spokeswoman said Mr. Cameron and his wife took responsibility for the incident. “They are their children and they take responsibility for them,” she said. “No one is going to face disciplinary action. This was an error.”