There is one other matter that hasn't been fully investigated in the story of Sydney's search for a postwar tram. The investigation of alternatives like the SW6 took place in the context of the upcoming award of a contract for R1s to Comeng, which was the only bidder (Clyde wasn't in the running) and their price was quite high.
It may have been high for a reason - that they didn't want an order. What was happening at Comeng Granville at that time was a huge build-up of their bus business. There were enormous orders for hundreds of buses after the war (500 double deckers for DRTT alone) and Comeng saw this as a huge business opportunity and a significant part of their future. They built a new workshop for buses alone. Trams on the other hand had little future at that time and little profit.
Nobody has ever questioned this oft-cited "postwar steel shortage" that apparently poleaxed the R1 order in the context that there was somehow plenty of steel for hundreds of buses, not to mention trains.
I suspect that, quietly in the background, Comeng was also in on the game to bring the Sydney trams to an end because, if they were gone, there were lots more bus orders to make up for it, whereas if the trams remained, they wouldn't need renewing so often and nowhere near as many buses would be needed. Unfortunately John Dumm took the "steel shortage" claim at face value when he researched the company history, so it was never put to the test of further investigation.