In September last, a man was arrested in a state room after he scaled the fence of Buckingham Palace. After which there is a full-scale security review.

Police said the unnamed 37-year-old was found at night (10.30 p.m.) “in an area currently open to the public during the day”. He was arrested for burglary, trespass and criminal damage. A second man, 38, was arrested outside the palace for conspiracy to commit burglary. The two men have been bailed while the police investigation continues.

It is believed that the intruder entered one of the 19 state rooms after scaling a 12-foot fence and kicking down a poorly secured external door.

The palace’s state rooms — those designed for monarchs to “receive, reward and entertain their subjects and visiting dignitaries” — have been open to the paying public during August and September for the last 10 years.

The ease with which the man gained access will concern officials, although no member of the royal family was in residence at the time of the break-in.

Royal officials insisted there would never be another security breach at the palace following the case of Michael Fagan on July 9, 1982. Fagan walked into the Queen’s bedroom as she slept, and it was reported at the time that the 31-year-old unemployed father of four spent around 10 minutes talking to the Queen after he had climbed over the palace walls and up a drainpipe.