Bus drivers have been warned to watch their speed after one was spotted lighting up warning signs in Cheam.
The Kingston to Sutton 213 bus was spotted triggering a light-up 30mph warning sign meaning it was breaking the speed limit in Malden Road on January 20.
Sutton Bus Garage in Bushey Road
Police have visited the Sutton bus garage, operated by Go Ahead London, to flag up the incident and bosses have promised to speak to drivers about their responsibilities.
A member of the public reported the matter to police after seeing the bus illuminate the sign.
Although the incident indicated the bus was speeding, no formal prosecution can take place as the speed would need to be recorded on a speed gun or camera.
But police have been in touch with the garage to warn bosses of their responsibility.
A spokesman said: "The bus garage has been made aware of this report and the matter has been brought to the attention of the driver.
"Our safer transport team is now working with the bus garage for them to advise their drivers accordingly."
The bus in question is operated by London General, a subsidiary of Go-Ahead London.
A Go Ahead spokesman confirmed a police sergeant visited the Sutton bus garage in Bushey Road on Tuesday.
He added: "He spoke to a member of management about the speed of the bus in question.
"We will make the drivers aware of the incident by the normal means of posting notices just to remind them of the need to watch their speed in residential areas."
The incident has also been flagged up to Sutton councillors who will also be monitoring drivers' behaviour.
Coun Mary Burstow said: "The message could not be clearer - If you spot a speeding bus or lorry, take down the time of day, bus registration and bus number."
Coun Tony Shields also encouraged people to contact the police if they see a bus breaking the speed limit.
If you see a speeding bus you can contact police on 101.