Image copyright London Fire Brigade Image caption Birds had often been seen flying into a hole in the roof

A bird carrying a lit cigarette to its nest has been blamed for starting a fire in a building in south London.

London Fire Brigade investigators believe a bird took the smouldering butt to its nest on the roof of the building in Landor Road, Stockwell.

Matt Cullen, who examined the scene after the fire on Wednesday night, said he was "baffled" at first.

"The smoking gun was found when we discovered a partially burnt birds nest," he said.

The blaze damaged about a fifth of the building's roof and nine people were evacuated.

'Crazy' fire

Mr Cullen 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.

"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."

Richard Scroggs, who runs The Old Post Office Bakery in Landor Road, remarked: "It's crazy isn't it?

"Smokers. What can you say? I'm glad I gave up."