A street cleaner struck gold when he found a Rolex watch down a drain.
The 28-year-old was cleaning a drain near Chalkwell railway station in Essex last Friday when he found the watch among the dirt.
When he took a closer look, he found it was an 18-carat gold Rolex worth £21,000.
The worker, who does not wish to be named, handed the watch in at his nearest police station.
But it had not been registered lost or stolen and, if it is not claimed within 30 days, he will be allowed to keep it.
Pc Calley Mackay, of Essex Police, said: "This was a highly unusual find and it's hard to imagine how something so valuable has not been reported lost or stolen by its owner.
"If you recognise it and believe it may be yours, please contact me.
"However, through the serial number we do know a little about the watch's origins and will thoroughly check any claim to ownership, so only honest people need apply."
The watch is a yellow gold Rolex Oyster Perpetual Cosmograph from the Daytona collection.
Pc Mackay can be contacted at Southend police station on 101.