While investigators were unable to determine the exact cause of the blaze, a large caravan was noted as an early area of where it began.
Firefighters added they had not fully discounted that it was deliberate, a discarded cigarette or sunlight on a glass fragment.
An examination of the scene and video evidence found that the fire originated “in or around” the bottom of one of the gardens, although given the wind direction it could have started on the marshland to the rear.
A large static caravan was noted as the “perceived area of origin”, as it rapidly caught fire and helped the blaze spread.
In total the fire spread across 40 hectares, damaging 17 houses, five garages, 12 stables, a car repair workshop and several vehicles, as well as numerous sheds and outbuildings.
The investigator wrote: “Having called the brigade, [the neighbour] attempted to stop the fire spreading using a hosepipe, however, this had little effect.”
The conditions were “exceptionally hot and dry”, the investigator added, which meant the flames could easily move along the marshland to the rear of the properties.
LFB were able to stop a grass fire spreading to a diesel tank in the yard of Wennington Fire Station, which neighboured the yard containing hazardous cylinders.
Havering Council leader Ray Morgon said: “The fire caused massive disruption to residents in Wennington.
“We continue to be there