A small point.
Wikipedia's entry on the Canberra Express _ https://en.wikipedia.org/wiki/Canberra_Express
- claims that:
"The Canberra Express was an Australian passenger train operated by the State Rail Authority between Sydney and Canberra via the Main South line from May 1982 until January 1994.
It was introduced in May 1982 being operated by DEB railcar sets. In August 1983 it was converted to XPT operation and renamed the Canberra XPT. In February 1990 the XPT was replaced by HUB/RUB rolling stock]
It ceased in January 1994 following the introduction of Xplorers to the route."
Wikipedia's entry on the Canberra Monaro Express - https://en.wikipedia.org/wiki/Canberra_Monaro_Express
"The Canberra Monaro Express was a passenger train operated by the New South Wales Government Railways between Sydney, Canberra and Cooma from May 1955 until September 1988.
It was formed by two four-carriage DEB railcar sets and replaced the steam-hauled Federal City Express.
After departing Sydney Central it travelled via the Main South line to Goulburn where it branched off to Queanbeyan. There the train divided, with one set going to Canberra, and the other to Cooma.
The train normally consisted of two DEB railcar sets of four carriages. In July 1973 it was cut back to a single four-carriage set serving both Canberra and Cooma, sometimes with a non air-conditioned 620/720 set attached when demand warranted. Reliability problems with the DEB sets saw locomotive hauled trains take over the service between June 1981 and August 1982. In the State Rail Authority era it was built up to seven-carriage DEB sets serving Canberra and Cooma, before the old practice of dividing the train at Queanbeyan, with three cars going to Cooma, was reverted to in March 1986.The final Canberra Monaro Express ran on 26 September 1988."
I recall catching a loco-hailed service to Canberra in 1977.
Maybe an informed Railpager could sort this out?.