Many thanks Mobyturns and Woodturnerjosh!
It was indeed the clamping collar - got it off with a 3/16" hex key (and some light encouragement with a screwdriver to get it off after that), and that revealed a slot for the tommy bar, which made it easy to get the faceplate off using the supplied wrench!
Only had a few minutes to turn something, but despite not having turned on a lathe in 10 years, I successfully roughed out a spare chunk of Bunnings pine without putting a chisel through my foot :). The VL150 sure does feel like a nice piece of machinery!
Cheers,
Danny