Acacia dealbata and Acacia baileyana do hybridise, but with 4 pairs of pinnae, large individual pinnules and the bottom pair facing back to the stem it is pretty close to being a classic example of Cootamundra Wattle
Thanks Michael. Time to get the chainsaw and herbicide out. I have walked past this many times but up until now I just presumed it was a dealbata. This time, something didn't quite look right.