Ji Gantor, am I allowed to answer this one or do you want it to run a bit longer?
This person was a local rider in Bulimba, Brisbane who practiced trials in bushland near my parent's house and watching him practice was one of the main reasons I got into trials.
He successfully campaigned on TY250A (as you can see in the photo), TY250B, TY175C (or JC can't remember) and KT250.
He and the KT250 achieved legend status for me at least at a NDMTC Open trial at Lacey's Creek when after bending a shockie and not being able to get it moving freely again, just left it off the bike and finished the trial riding with one shockie - and won A grade to boot. I can still remember the way the bike went over the muddy uphill climbs over rocks with the rear suspension bottoming out repeatedly and harshly but he held his line and cruised through, and the swingarm still looked straight at the end of the trial. I guess that has something to do with the bike being made by Kawasaki Heavy Industries and mystery rider being only about 65kg.
And for pmc57, mystery rider is 3 years older than Craig Gillies.