I came across a review of Rex and Heather Gilroy’s Blue Mountains Triangles in Nexus magazine. (So of course I had to order the book. ) I’m not familiar with these events but a quick internet search revealed all kinds of links to sites with information on this fascinating UFO area.
It’s not strictly Vintage UFO, since sightings are on-going. But according to the review in Nexus:
Unidentified flying objects of an array of shapes have been seen around the vast wilderness region of the Blue Mountains west of Sydney, Australia since 1875 when colonial settlers in the Kurrajong area reported “a gigantic, squarish flying craft.” (italics mine)
This photo was taken in 1954 by W.C. Hall in Australia.