Used in N. Ireland during the troubles, along with whatever other machines were in use for dropping patrols or ground observation.
They tended to keep low (obviously), you could hear them a mile off but suddenly from nowhere they flew overhead and onwards. Same with the smaller ones that dropped patrols in bandit country.
There was a smaller type that was used for ground observation. High in the sky over west Belfast, they seemed like a fixture. Nailed to the sky and emitting a constant background engine noise, they seemed to be permanently there.
At night you could be driving along and suddenly your car and a large circle of intense light would illuminate you and your surroundings. It was like the scene in close encounters of the 3rd kind. You were being checked out from above.
Davy