Seven fire engines and around 50 firefighters were called to a grass fire on Oaks Lane in Newbury Park.
An area of farmland of around 15 hectares was badly damaged by the fire. A number of properties in Oaks Lane were evacuated by the Metropolitan Police Service and five horses were led to safety. There were no reports of any injuries.
A London Fire Brigade spokesperson said: “The warmer weather we have been having makes the ground extremely dry, which unfortunately means grassland, parks, undergrowth and woodlands will burn quickly when exposed to even the smallest of sparks.
“We don’t want people to be complacent and that means not barbecuing in parks and open spaces, ensuring cigarettes are properly disposed of and clearing away rubbish and glass as they can magnify the sun and cause a fire.”
The Brigade's 999 Control Officers took 37 calls to the blaze.
The Brigade was called at 1632 and the fire was under control by 1854. Fire crews from Barking, Dagenham, Ilford, Romford and surrounding fire stations were at the scene.