Following sjbatche's lead I did I bit more digging. After arriving in NZ the Yanchep was rename Tuahine and is still working here now. I was able to find a few photos online and have contacted the current owners.
It may have a hull similar to the Bronzewing class but the wheelhouse is quite different. The original, as seen in the photo above, was extended prior to its arrival in NZ.
There is a true Bronzewing class tug operating in Auckland – the Mollymawk. Both of these tugs would make great subjects and now I'm torn between the two of them. Mermod and sjbatche have both built very nice Bronzewings. Decisions, decisions. I might have to toss a coin. Or build both.
A bonus from this investigation has thrown up a new photo of the Yorke Syme, which I've been trying to track down for a while. It is moored and disused near Auckland and had a fire while unattended recently. At least I know where it is now.