Fire crews from Sutton, New Malden and Mitcham tackled the blaze which is thought to have been caused by faulty electrical equipment.
One eyewitness (who sent in these photos of the incident) told the Worcester Park Blog:
"The fire brigade were in attendance within ten minutes [and stayed] until 12.30am. The thick black smoke pouring out the upstairs windows drew quite a crowd - or it may have been the firemen!"
London Fire Brigade Watch Manager Paul Gouk said the incident highlights the need to install smoke alarms:
“All the doors upstairs were opened which can fuel the spread of fire. Fire crews worked hard to stop the fire from spreading to surrounding rooms and to the ground floor.
There was no smoke alarm in the property and the residents were alerted to the fire by hearing breaking glass. I would urge all Londoner’s to buy one and test the battery once a week.”