A retired couple had to tackle a blaze in their hallway after an arsonist poured flammable liquid through their letterbox and set it alight.
Police are appealing for witnesses after the attack in Dower Avenue, Wallington, in the early hours on November 1.
The couple, who were sleeping upstairs at the time, were saved by their smoke alarm which went off at 6.25am.
The blaze had not taken hold of the entire hallway and the couple were able to put the fire out with their extinguisher.
However the front door was destroyed and the walls and ceilings were blackened by smoke.
The arsonist is described as a white man who was carrying a large Nike golf umbrella. He was wearing a golf style raincoat, baggy trousers, possibly over the top of other trousers, and thick gloves.
Detective constable Emily Marshall, of Sutton CID, said she is keen to hear from members of the public who can help the police investigation into this seemingly motiveless attack.
She said: "Please come forward if you saw a man of this description in the area of Dower Avenue, Woodcote Avenue or Park Hill Road - all addresses in Wallington - on November 1 between 6am and 7am, or if you have seen anyone acting suspiciously in the area recently."
Sutton CID can be contacted on 020 8649 0747. Alternatively, you can contact Crimestoppers, an independent charity, anonymously on 0800 555 111