A police box is a public telephone kiosk or callbox for the use of members of the police, or for members of the public to contact the police. It was used in the United Kingdom throughout the 20th century from the early 1920s. Unlike an ordinary callbox, its telephone was located behind a hinged door so it could be used from the outside, and the interior of the box was, in effect, a miniature police station for use by police officers to read and fill in reports, take meal breaks and even temporarily hold detainees until the arrival of transport.
The TARDIS "Time And Relative Dimension In Space" is a fictional time machine and spacecraft that appears in the British science fiction television series Doctor Who and its various spin-offs.
The TV show Doctor Who mainly features a single TARDIS used by the central character the Doctor. However, in the series other TARDISes are sometimes seen or used. The Doctor's TARDIS has a number of features peculiar to it, notably due to its age and personality. While other TARDISes have the ability to change their appearance in order to "blend in" with their surroundings, the chameleon circuit in the Doctor's TARDIS is broken, and it always resembles a police box. However, in the new series, a "perception filter" is used to blend in with the surroundings so it is often ignored by passersby. While the exterior is of limited size, the TARDIS is much "bigger on the inside," containing an apparently infinite number of rooms, corridors and storage spaces within.
Doctor Who has become so much a part of British popular culture that the shape of the police box has become associated with the TARDIS rather than with its real-world inspiration. The name TARDIS is a registered trademark of the British Broadcasting Corporation (BBC). The police box design has also been registered as a trademark by the BBC, despite the design having been created by the Metropolitan Police. The word TARDIS is listed in the Oxford English Dictionary.