I live on the side of a hill. Across the valley is a travellers site. About 3/4 times a week a yellow helicopter comes along very low just skimming the forest trees. When it gets to the camp it hovers over it just skimming the caravan roofs. It then turns round and flies off. It is very deliberate. Why would it do this?
OP says it was yellow, therefore NOT a police helicopter. The navy blue with yellow roof area (for want of a better word) of police helicopters is to enable it to be distinguishable to other air traffic.
I know it costs the ratepayers an arm and a leg every time the police use their helicopters, so by default it must be a power company as they are rolling in dosh.