Police have launched an investigation after a set of keys were stolen at the Tower of London on Guy Fawkes Night.
The keys were taken from a metal box that was supposed to have been locked. They were in a sentry box outside the main walls.
The set of keys opened drawbridges, a conference room and a restaurant, with the Tower forced to spend thousands of pounds replacing locks.
Guards spotted the thief but could only radio for assistance as strict rules mean they cannot leave their post to give chase.
The Met Police confirmed that they had received a report of theft and it is being investigated by Tower Hamlets CID.
A man was apprehended inside the main gate of the perimeter fence.
The tower is traditionally guarded by Yeoman Warders – popularly known as beefeaters - but are supported by a private security team.
Tower chiefs insisted that the Crown Jewels were never at risk of being stolen and the walls were never breached.
A Historic Royal Palaces spokeswoman said: “We can confirm that an incident took place in the Tower environs in the early hours of November 6 and that this is now a police matter, so we are unable to discuss details.
”We can however confirm that during this incident, keys for a restaurant and conference rooms were taken together with a key to an internal lock to the Tower drawbridges that is not accessible from the outside.
“It would not have been possible to gain access to the Tower with any of these keys. All the affected locks were immediately changed.
”We have carried out an internal investigation and have concluded that our well-established security systems and procedures are robust.
“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.”