Which Breed of Owl?

This bird was photographed near the Leversha Reserve in Montrose, at the foot of the Dandenongs in Victoria. It was quite large but as it was high up it was hard to estimate the size.

Would appreciate it if anyone could identify this bird.

http://s277.photobucket.com/albums/kk55/neddyhow/?action=view&current=Owlcopy2a.jpg