My grandmother owned the TV in the 60s, and Trek would have come on at 8.30pm or later - and we were already in bed. Colour TV came to Australia in late 1975 and about ten random episodes of TOS were selected to show off its capabilities. De Forest Kelley's eyes were so blue! I wish I could recall which eps they aired, and which ones I saw first. I know one was "The Devil in the Dark" because I somehow remembered the "No Kill I" message before reading the Blish adaptation in 1980. Another was "Spectre of the Gun". The most memorable was "What Are Little Girls Made Of?", with Kirk being spun on the android duplicator device. I think "The Corbomite Maneuver" was there, too, because we recognised the voice of Lurch and, of course, Ted Cassidy turned up in WALGMO as well.
I had seen first-run eps of TAS before, in b/w on Saturday mornings. Again, only random eps.; definitely "Yesteryear", "Bem", "More Tribbles, More Troubles", "The Counter-clock Incident" and "Albatross". When TAS shifted to weekday mornings, during the colour TV launch, my brothers and I looked forward to seeing the Auroral Plague turn the crew different colours. A friend remembers that every time "The Pirates of Orion" played on Australian TV, Acts 2 and 3 were mistakenly reversed. This was finally corrected in the 1990s reruns.