Officials at the Tower of London have been forced to change some of the locks after an intruder broke in and stole a set of keys.
Tower chiefs say there was never any threat of the Crown Jewels being taken, but admit security procedures "were not carried out to the expected standard". The keys gave access to the site's drawbridges as well as conference rooms and a restaurant.
A spokeswoman for the Historic Royal Palaces 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... 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."