Historical information

X48 entered service in 1977 (Wikipedia https://en.wikipedia.org/wiki/Victorian_Railways_X_class_(diesel))

The car immediately behind the locomtive is State Car No. 2 (Melville) which was used as a power unit for the train.
https://www.pjv101.net/cd/pages/c160v03.htm

Train of Knowledge
https://en.wikipedia.org/wiki/Train_of_Knowledge

The Train of Knowledge was an Australian school camp on wheels, allowing students and teachers to visit multiple locations around Victoria without having to organise accommodation or transport.

The train was formed originally with whatever rolling stock was available, but within a few years it had settled to a standard consist made up to carry between 80 and 90 school children, 6 teachers and four railway staff members.

As of 1976, the consist used up to five of the six available E type sleeping cars, each with 20 berths, plus the shower car Carey, formerly a horsebox, Melville, a former royal carriage used to provide power for lighting, heating and cooking, 43BPL (a former sitting carriage) used as a classroom, and Avoca as the dining car for the train, with 48 seats allowing serving the whole train meals in two sittings.

Physical description

Digital TIFF file
Scan of 35mm Ilford FP4 black and white transparency