Her Majesty suggested the financial crisis of 2008 had happened because the Financial Services Authority “didn’t have the teeth” to rein in the biggest risk-takers, the Daily Telegraph reports.

The Duke of Edinburgh, meanwhile, had a typically blunt piece of advice for the Bank’s executives: “Don’t do it again!”

The Queen and the Duke grilled Bank of England staff during a visit which included a tour of a vault stacked with £27bn worth of bullion.

Suit Kapadia, one of the Bank’s financial policy experts, said he wanted to answer a question the Queen asked academics at the London School of Economics in 2008 about why no one saw the financial crisis coming.

“Oh!” said the Queen, looking slightly taken aback.

Kapadia said the City had got “complacent” because it thought risk was being managed better than it was, and the financial system had become too interconnected.

The Queen agreed: “People got a bit lax … perhaps it was difficult to foresee.”

She asked if the financial system was less interconnected now and suggested that part of the problem had been the lack of powers given to the Financial Services Authority. “They didn’t have the teeth,” she said.

The Duke, meanwhile, was typically direct. “There’s not another one coming, is there?” he asked. Then, as he left Kapadia and his group, he said: “Don’t do it again!”