A 90-year-old woman had to be rescued from her flat after leaving a plastic tray on top of her cooker.
The tray smouldered and filled the flat in Hendfield Court in Beddington Gardens from floor to ceiling with smoke but the woman had taken the battery out of her smoke alarm meaning she was unaware until a chance visit from her carer.
Firefighters, who were called to the flat shortly after 7.30pm on Tuesday, said the outcome could have been much worse had the woman's carer not come around when she did and opened the door to see smoke billowing out.
A spokesman said: "She had a smoke detector but for whatever reason she removed the battery. We just want to stress the importance of having a working smoke alarm and of testing the battery.
"God knows what would have happened if the carer hadn't come round."
Following the incident, firefighters will be fitting smoke detectors at other flats in Hendfield Court next week.
To get your fire alarm tested or to have one fitted for free, you can call London Fire Brigade on 0208 555 1200.