The theft of a road sign which frowns or smiles at motorists depending on their speed is puzzling council bosses.
The sign flashes up a frown when drivers are over the speed limit
Oxfordshire County Council had hoped the theft was some kind of "festive joke" and the device would be found somewhere "dressed up or decorated".
But the Speed Indicator Display (Sid) sign has not turned up since it was taken from the A417 close to Harwell village on 21 December.
The council has now notified the police who are investigating the incident.
Steve Wood, county speed management strategy officer, said: "Oxfordshire has been using these signs for almost five years.
"By now drivers should know that these aren't enforcement cameras and they don't record any details of a vehicle being driven too quickly.
"They have been very successful in keeping most drivers within the speed limits, especially in villages.
"Other than two small rechargeable batteries inside, there isn't anything of monetary value to anyone."