A small point of order towards the end, it was very rare to see red rattlers on the eastern suburbs / illawarra lines. This went all double deck early on.
With the opening of the Eastern Suburbs Railway back in 1979, all services between Bondi Junction, Cronulla and Waterfall were scheduled to be operated by double deck stock. For all intents, the use of single deck stock was banned, although there was no reason operationally for this to be the case - just political to be able to say that one part of the network was "all double deck stock".
When Approval was finally obtained for the single deck Heritage Electric Train to operate as part of an excursion over the Eastern Suburbs Railway, Officialdom decreed that the special train should be preceeded or followed by (I forget which now!) by a 46 class electric locomotive, "just in case of failure!". I have a photo of the 46 class proceeding into the Illawarra Relief tunnel near Erskinville, and of the Heritage Electric Train passing through the site of Woollahra "station". On a later occasion, the original single deck "Zoo Train" was able to make the trip unescorted to Bondi Junction - I also have some photos of the train at Bondi Junction station.
I am aware of only one occasion where a single deck (suburban) set made it to the ESR tracks. Details are now vague, but memory suggests that it was on a holiday weekend and as a result of a set failure of the normal double deck set.
Perhaps the most unusual single deck set to operate over the line was 9-car end-platform DUB.63, hauled by double 73 class. This train made numerous journeys over the line prior to its official opening ... it became a very popular operation, run by "the Railways" as a public relations exercise.
Possibly even a more unusual occasion occurred when the "Sydney Express" overnight train from Melbourne was diverted to the ESR in error at Erskinville Junction. The train crew accepted the turnout signal and the train proceeded as far Central 24 (underground) platform where it was terminated. Being no turnback facility for trains in this direction at Central 24, the Express had to be towed back on the wrong lin e back to Erskinville Junction, before being able to continue on its more usual path into Platform 1.