It is considered a shocking breach of etiquette to reveal what, if anything, the queen tells you, especially when it comes to political views, which she is technically not supposed to have. The BBC immediately issued an abject apology, saying that the correspondent, Frank Gardner, was completely out of line.

“The conversation should have remained private, and the BBC and Frank deeply regret this breach of confidence,” the broadcaster said in a statement. “It was wholly inappropriate. Frank is extremely sorry for the embarrassment caused and has apologized to the palace.”

Buckingham Palace said it would not comment on the matter.

The episode occurred on BBC Today, an influential public-affairs morning radio program. Mr. Gardner, the broadcaster’s security correspondent, was speaking about Abu Hamza, an Egyptian cleric who settled in Britain and preached violent anti-British jihad at a North London mosque.

The British government has been trying for years to extradite Mr. Hamza to the United States, where he is wanted in connection with, among other things, accusations of trying to set up a terrorist training camp in Oregon. On Monday, the European Court of Human Rights ruled that the extradition would not violate his human rights, a finding that clears the way for Mr. Hamza’s removal from Britain.

As Mr. Gardner discussed the case, he was suddenly overcome by a desire to name-drop perhaps the biggest name it is possible to drop here. In Britain, where most people like the queen, even if they do not necessarily like her relatives, she is usually regarded as an admirably restrained cipher whose public statements are deliberately bland, even banal. It seems surprising, in a way, that she has opinions at all, so much has she perfected the art of meaningless small talk along the lines of, “Have you come far?”

Not to Mr. Gardner, though.

“Actually, I can tell you that the queen was pretty upset that there was no way to arrest him,” he blurted out, speaking of the time some years ago when Mr. Hamza was still operating freely at the mosque. “She couldn’t understand — surely there was some way to arrest him?”

The program’s clearly shocked host, James Naughtie, then said, “That’s a fascinating piece of information, Frank.”

“Yes, I thought I’d drop that in,” Mr. Gardner replied. “She told me.”

“Drop it in?” Mr. Naughtie said. “It’s a corker.”

Mr. Gardner then went on blithely to reveal that the queen, who as head of state is not supposed to intervene in governmental affairs, had “spoken to the home secretary at the time and said, surely this man must have broken some laws.”

The BBC reported that David Blunkett, who could have been the home secretary Mr. Gardner was referring to, denied that the queen had raised the issue of Abu Hamza with him.

People in the past have let slip things that the queen supposedly said to them. Last year, the former girlfriend of a prominent Labour member of Parliament said that at a Buckingham Palace Christmas party for politicians, she heard the queen telling a Turkish woman that she opposed Turkey’s entry into the European Union, which was “getting awfully big.”