The mention of Woolies pick and mix has just given me horrendous flash backs. Essentially sugar, dyed in different colours and various shapes My teeth feel like they've been carpeted just with the memory of it.Very much like the micron thin layer of chocolate 'product' that goes on Wagon Wheels (Waggon Castors?). Strange stuff with a faint, whitish, powdery bloom on the surface. As you say, very similar to doggy drops or those awful chocolate drops you used to get in Woolies pick 'n' mix, which were probably supplied by the same people. Even as a kid, I never saw the appeal of Wagon Wheels. They always tasted stale to me.
The chocolate layer on Jacob's Club biscuits was always of a superior quality but as the years progressed, that also became transparently thin.