Post box

A post box was for sending post. People would put post into the box through the slot, and the postman would collect it.

In the United Kingdom, post boxes were typically coloured red, (TV: The Idiot's Lantern ^[+]Loading...["The Idiot's Lantern (TV story)"], Regeneration ^[+]Loading...["Regeneration (TV story)"]) the colour of Royal Mail. (TV: The Christmas Invasion ^[+]Loading...["The Christmas Invasion (TV story)"])

A post box was the last shape the Doctor's TARDIS took before it became a police box. (PROSE: The Little Things)

A post box