Mr A – you're thinking of Ivo Obregon and yes you're right, he was responsible for some of the "better" trails around here.
As for the Knicker trail, i wish you'd call by it's proper name – Jerry's trail (after local rider Jer Humphries…. first man to clean it!
And the off camber trail to the left of picnic bench is called Chamonix….. apparently
Oh yes, nearly forgot, i remember when 50 acre was just god old Porn trail…….. Ah, good days…