30s or early 40s Thai in a dark jacket. The dark jacket made me think he was perhaps an airline employee or with some government agency, so maybe he was an air marshal. On a 747 I would think an air marshal might be seated on the upper deck though.

Are air marshals commonly on TG int'l flights? Does the government feel there is a threat of terrorism, or are they there for other security reasons?

I was the only foreigner in the cabin. Could it be that one of the other F pax was a vip or government official, and this person was providing security?