HI. Lovely photo and you have answered the question I have asked many times.
I live in Emu Heights on the escarpment of the Blue Mountains and every few weeks or so we see this bird flying around, or I should say gliding around. Always around 200-300 foot (at a guess) off the ground over the grass padocks at the base of the mountains, just near the Nepean River. Obviously hunting for food, rabbits or rodents.
We always thought it was an Eagle but although it is quite big and looks strong, it didn't seem quite large enough to be an Eagle and a friend said it was a Kestrel, but they are smaller and I don't think you get them around here.
I think that you have pinpointed the bird that has puzzled us for ages. Thank you, I can now look for further information and hopefully confirm what it is.
But yeh, I love the photo.