A bird carrying a lit cigarette to its nest is believed to have started a major fire in south London last night.

Fire investigators think the bird nicked the smouldering butt from the street below and dropped it into its nest in the roof area of the building in Stockwell, causing it to catch light.

Fire investigation officer Matt Cullen, who examined the scene, said: “When we got up into the roof, we were baffled as there were no obvious ignition sources – no one had been up to there for a long time and there were no electrics that could have sparked a blaze.

"We looked everywhere, but the smoking gun was found when we discovered a partially burnt birds nest. Neighbours told us they often saw birds flying in and out of a hole in the roof. We believe that one of the birds picked up a cigarette butt that was still smouldering and dropped it into the nest, causing it to catch fire and set the roof alight."

Four fire engines and 21 firefighters and officers went to the blaze on Landor Road in Stockwell after being called out at 10.23pm. The fire was under control at 12:39am.

The fire damaged around a fifth of the roof area but no one was hurt. Nine people escaped the building before crews arrived.

Officer Cullen added: “The incident is a great example of why it’s important to put your cigarettes out fully – you never know what might become of your smouldering butts! Luckily for the residents, their neighbours saw the smoke and raised the alarm, so fire crews could get in quickly and bring it under control.”

The type of bird responsible is unknown, although some have suggested it may have been a Puffin...