The Tower of London has been forced to change its locks after a thief broke in and stole a set of keys.

Managers confirmed keys for a restaurant, conference rooms, and to the Tower drawbridges were taken from the site in the early hours of November 6.

A spokesman for the Historic Royal Palaces said an internal investigation found their security systems and procedures were robust.

“It would not have been possible to gain access to the Tower with any of these keys,” she said.

“All affected locks were immediately changed.

“However on this occasion, these procedures were not carried out to the expected standard. A staff disciplinary procedure is under way to address this issue.”

The keys were taken from an opened metal box, according to today’s The Sun newspaper.

The Tower Hamlets attraction, which contains the Crown Jewels, is guarded by Beefeaters with help from a private security firm.

It was reported the guards were unable to leave their positions to chase the alleged intruder.

A Metropolitan Police spokesman said: “We received an allegation of theft and it is currently being investigated by Tower Hamlets CID.”