Firefighters were pressed into service to tackle a blaze at a farm in West Middlesex.
The fire broke out in a 14ha field of hay at Pinnerwood Farm in Pinner on Tuesday evening (9 July).
London Fire Brigade sent three fire engines to the field and on arrival they found a large amount of haylage was alight.
Firefighters used water cannons to get the fire under control quickly and stop it spreading to other fields. However, around 10t of haylage, worth an estimated £700, went up in smoke.
David Angold, tenant farmer at 50ha Pinnerwood Farm, said children were spotted fleeing the scene shortly after the fire started.
“I get a bit despondent sometimes. You grow the crops then someone writes them off for you,” he added.
It is the second time in a few weeks emergency crews have responded to a fire at the farm. In May, fire tore through a barn wiping out 180t of hay.
A spokesman for London Fire Brigade said: “We sent three fire engines – one from Harrow and two from Northolt – following reports of a fire in a farm field at Colburn Avenue, Heath End, Pinner.
“They were called at 7.48pm and the fire was under control at 8.53pm.”
Despite reports that the fire was deliberately started, it was not under investigation, he added.