British Crown Jewels
From Tardis Wiki, the free Doctor Who reference
The Crown Jewels were, at some point, kept in the Tower of London.
Missy, using her vortex manipulator, was able to break into the Tower to steal the jewels. The Twelfth Doctor entered the room, barely missing the chance to stop her from again jumping into the Time Vortex. (PROSE: Dr. Twelfth)