The University of Newcastle Cultural Collections has this image of an etching of Lambton, that is dated “c. 1880’s”. Here’s my attempt to narrow down the date more precisely, assuming that the creator of the etching hasn’t left things out or added things in for artistic reasons.
The first thing to note is in respect to two major Lambton buildings – the etching shows the Post Office in Morehead St, but not the Mechanics Institute in Elder St. This unequivocally dates the etching in the period 1884-1894.
Secondly, in the Elder St and Morehead St corner of Lambton Park, the council chambers built in 1887 is absent.
Thirdly, in looking at Lambton Park, it is noticeably empty – no buildings or trees or paths. This would suggest that the etching is from a time shortly after the land was cleared of houses (1884) and before any substantial work on developing the park commenced. Close inspection of the etching shows that the park is surrounded by a sawn picket fence, which again dates the etching to post 1884. Another article from 1885 says that a second shorter fence was being built around the park, twelve feet in from the outer fence. There is no sign of this second inner fence in the etching.
Putting all this together I would suggest that the date of the etching is 1884 – 1885.