Thief scales Tower of London walls to steal drawbridge keys from unlocked sentry box in embarrassing security blunder Police have launched an investigation after a thief broke into the Tower of London on Guy Fawkes Night and stole a set of keys. The thief is thought to have scaled the Tower's Front Gate and an inner wall, before climbing in to a sentry box and stealing the keys from a metal box that was supposed to have been locked. 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 pleas for back-up were ignored, however, and the raider subsequently escaped. The Met Police confirmed that they had received a report of theft and it is being investigated by Tower Hamlets CID. The tower is traditionally guarded by Yeoman Warders - popularly known as beefeaters - but are supported by a private security team.