Last night (at about 11.50 pm) I heard some very close. On looking out of my window, I saw the sillhouette of one perching on the top of this television aerial on a nearby house and could hear it (and at least one other more distant) hooting. So they may be exploring residential areas too.

Awesome - thanks for letting me know. I'm recovering from a chest infection, but I'll open the windows tonight and listen out :)