Bit of an update.
I did get some dash representation of what's going on with mixture in the form of an AFR gauge - see pic.
The number it shows seems to correspond to petrol stoichiometry as when I checked it against O2 Voltage showing on the AEB software when the O2 Voltage was 0.5V and the display on the circumference of the dial was at midpoint the number showing was 14.7.
By what I've seen in running, my motor has a tendency to run a touch rich - circa 14.2:1 (corrected for LPG). It occasionally holds that as a steady value but usually is between 13.8 and 15.6:1 (corrected for LPG) which averages at 14.2:1 with occasional swings to 16.9:1.
Took a closer look at the pump I draw LPG from (forgotten the brand/type) and absolutely no reference to temperature or any correction w.r.t. I suspect this is quite an old pump.