Four fire engines and around 25 firefighters attended a fire at a school ground on Kidbrooke Grove in Blackheath.
A derelict club house on the school ground was destroyed by the blaze.
Firefighters worked hard to stop the blaze and stop it spreading. There was nobody in the property at the time of the fire and no injuries were reported.
Sub-officer Ian Woodhams, who was at the scene, said: “This fire could have been far worse. Though the building is derelict and not used, the electricity in the building was still switched on, which is in itself a fire risk.
“If you know a building is not going to be in use, make sure that it is properly locked up and secure.
“Ensure that power supplies are switched off or removed altogether.
“A Neighbourhood Watch scheme can alert public authorities if any potentially dangerous or suspicious activity is spotted in or around an unused building.”
The Brigade were called at 2028 and the fire was under control by 2157. Fire crews from Lee Green, Lewisham, East Greenwich and Greenwich fire stations attended the scene.
The cause of the fire is under investigation by the Brigade’s Fire Investigation team and the Metropolitan Police.