Probably better know today as a 'Tardis' from the TV series Doctor Who, Police phone boxes were used in London from the 1920's.
Although not in use in London today, there are still a few refurbished Police Boxes in London.
This brooch is made from blue laser cut plastic with a mirror acrylic backing,
It measures 3.7 cm W x 7.2 cm H with a silver plated locking brooch pin on the back.
If you're interested in Police call boxes, this website had some great information: http://www.policeboxes.com/pboxhist.htm