They also used 2 firemen during the coal strikes after World War 2, when the VR was forced to run using wood.
Now you've really done it! There will inevitably be a few gunzels who'll either read that, or hear it secondhand, and they will forever believe that the SOP S class was wood fired in the 40's. (We do know that some goods locos were forced to use wood during the strike - not very good, but they made it somehow.)
As a matter of academic interest the calorific values of various fuels were as listed below ( taken from one of my father's old notebooks).
They are old figures in British Thermal Units per pound of fuel - apologies to metrics.
Maitland Coal: 13,594; Moisture 2.29%, Volatiles 38.37%; Ash 7.15%
Lithgow Coal:12,556; Moisture 2.28%, Volatiles 26.10%; Ash 11.09%
State Mine Coal (Vic); 11,458; Moisture 6.02%; Volatiles 24.4%; Ash 11.29
Best Brown Coal: 9,000.
Kiln Dried Firewood: 4,500 to 5,000.
Anyone tempted to believe that the SOP could have been wood fired can take one look at those figures and forget the idea.
Another look shows why there were strict orders that the SOP was always to have the bunker filled with best quality Maitland. It also shows why State Mine coal was regarded as NBG (got it, YM????)