Multiple fingers on the pressure plate were bent. Given how incredibly different the clutch feels now compared to how it always (not just recently) felt on the Monaro, I am suspecting that the pressure plate was in a bad way for a while before it finally gave in on Putty. One (or more) of the fingers bent so far that the plate could not flex and disengage. All fixed within 24 hours under warranty, including a 150Km tow truck journey. It wasn't even being driven hard at the time it went. There was no clunk, no bang, no nothing. Just all of a sudden when I went to shift from 4th to 3rd, I could not depress the clutch pedal. It felt exactly like something was preventing the cutch from operating, which turned out to be exactly the case.