Hi - As requested, I think I've worked out how to crop the first image I posted which enlarges the bird in the photos but unfortunately the clarity is still not so good - better than the smaller image though.
Thanks CCPK. Initially I wasn't even sure this was a waterbird. With the cropped image, I think it may be a juvenile of the Nankeen Night Heron, Striated Heron, and Bitterns species group, most likely Nankeen Night Heron in this area. Unfortunately I am not familiar with any of these species, high up on my would live to see list. I have to say I am quite surprised by the apparent smallness in size...