In these parts of the world, PO Boxes aren't really boxes. Instead good ol'
Royal Mail keeps the post aside in a big pile at the
sorting office. When the renter wants their mail back, they must present a
small pink card (which has their box number scrawled upon it), and
wait while the
postie on duty sorts through the pile in a room just
out of sight to try and track down the mail.
There are, I suppose, thousands of people who have to put up with this. I am number 3780.