How drones are hunting fires hidden beneath the Cairngorms

It is 06:00 and I'm meeting drone pilot Pete Short for a dawn patrol in the Cairngorms National Park.
It is a job he has been doing for almost three months, since a huge wildfire tore through this landscape in July.
The flames which swept across the hillsides are gone. From where we are standing, there is little to suggest there is still a fire here at all.
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