Do we have a Powerful owl visiting at night?

For the last couple of nights we have been listening to a very deep and resonant double hoot coming from the tree tops.  It is not a call with which we are familiar having previously heard and seen Boobooks, Barn and Barking owls and Tawny frogmouths around the garden.
Powerful Owls can be up to 55cm and larger for males so it would be wonderful to find its daytime roost to have a good look at him or her.  They feed on small possums, rabbits and some birds which certainly are in plentiful supply around the garden.  We shall keep looking into the tree- tops and keep an ear out for small birds that seem to have a knack for finding anything unusual in their territory!

There is a good web site here:- HERE which has a very good recording of its call; let us know if you hear one!  Col Hockings