The hat graveyard

Every police station has a hat graveyard.For some reason the hats come together as one, never to be re-claimed.What has happened to the heads that once owned the hats, have they retired, gone missing, been kidnapped?, this important question has never been raised on the Bill, or even Coronation street, it's time it had it's own programme "Police Hats the real story", but who shall head! the enquiry, I'll keep my ear to the ground.