I like the story of the "overflight" GSM. When I got posted to Hong Kong from Singapore to Hong Kong in January 1968 I flew up in a Bristol Freighter of the RNZAF. We refuelled in Qui Nohn in Vietnam in a 45 minute stopover, which was really interesting as I had never seen so many helicopters in my life.
I met a US Army officer who was on R & R in Hong Kong and when I told him this he said that had I been in the US forces that would have entitled me to the Vietnam Medal. A few weeks later I got a package in the post. The guy had got hold of one, complete in its box with ribbon bar etc. All entirely unofficial of course and I've never yet been tempted to wear it alongside my single GSM on Remembrance Sunday. Maybe one day.