I took the following photo's in a Lagoon on Sydney's Northern Beaches. There were a small group of these birds, about 3-5. They jumped all through the needle pine, never going lower than about 3 foot off the ground.
I think they might be Yellow or Yellow-rumped Thornbills.
.
.
Thanks Denis.
I was a bit stumped. The birds in the photos are almost entirely yellow, whereas the field guides have them with a greyish back and wings.