Thanks for the Glasgow Herald article, Archimedes, that answers my question. I certainly recall that at the time, in the eyes of most HK Chinese, the sentence was regarded as absurdly lenient, given that any PLA Soldier pulling the same stunt just the other side of the border would certainly face execution. By way of a benchmark, there's currently a mandatory five year sentence in UK simply for having an unlicensed/unauthorised firearm, even if it's locked in a loft/cellar with no criminal intent.