Six fire engines and around 40 firefighters were called to a disused barn on High Street in West Drayton on Saturday.
Part of the ground floor of a two storey barn was destroyed by the fire, there were no injuries reported.
Control Officers took the call at 1658 and mobilised crews from Hayes, Hillingdon, Feltham and other surrounding fire stations to the scene. The fire was over at1821.
The cause of the fire will be investigated by the Brigade’s Fire Investigation Unit and the Metropolitan Police Service.