Recently, the keys to the historic Tower of London were stolen, causing concern to authorities as the historical Tower houses the Queen’s Crowns jewels. Police are now investigating how exactly a burglar broke into the well-guarded castle and managed to steal several keys from the site’s sentry box before being apprehended.

The burglar was reportedly spotted by the Tower’s famous guards known as Beefeaters, but the guards did not immediately stop the suspect, instead staying at their designated posts and radioing for help. Without a chase, the burglar made off with keys to the Tower’s drawbridges and conference rooms and a restaurant, according to Historic Royal Palaces, the non-profit organisation that operates it. The Tower is one of the world’s major tourist attractions, with more than two million visitors each year.

“The intruder did not gain access into the Tower itself,” the spokeswoman said. “He did manage to get round the gate at the main entrance but was then apprehended and escorted off the premises.”

The Tower of London is guarded by both the Yeoman Warders, nicknamed Beefeaters, who each must have completed a minimum 22 years’ military service to guard the Tower, and a private security firm. Historic Royal Palaces defended its security protocol but also acknowledged the procedures were, in this instance, “not carried out to the expected standard,” and said they are pursuing a “staff disciplinary procedure.”