Firefighters made a surprise discovery when they found a cannabis factory in a house next door to a burning building.

They had been called to tackle a blaze in a two-storey house in Tavistock Avenue, Walthamstow, in the early hours of Monday.

A woman living there had managed to escape the fire after she was woken by a smoke alarm. Firefighters found her outside the burning house on the street.

While fighting the blaze, fire crews also wanted to evacuate neighbours who might have been at risk from the flames and smoke.

They forced their way into one of the next-door homes to make sure the residents were safe.

But instead of people hey were shocked to find cannabis plants being grown in the kitchen and bedrooms.

A police spokeswoman said: "It was a surprising find. Plants, believed to be cannabis, were being grown all around the house. The residents were not in but officers secured the scene."

A spokesman for London Fire Brigade said the blaze had not being caused by the cannabis factory and headded that the fire was not being treated as suspicious.

Serious damage was caused to the top floor of the house when flames ripped through the building just after 4am. It took 25 firefighters an hour-and-a-half to bring the fire under control. When they arrived at the scene, the whole of the roof was ablaze.

Walthamstow fire station manager Bob Selby said: "It was down to the hard work by firefighters that damage top the house was limited."