I zoomed in on the photo and I could not see any label that identified the unit as being made by Thandar. How can you tell it is a Thandar?
I also went to the Thandar website and none of the function generators shown appeared to be similar in packaging. Most companies tend to adopt a signature style to their equipment packages as part of their Corporate Image.
Sorry for the lousy pic (taken on phone). When I emailed thurlby Thandar, they said the one i had (serial number) was a sales demonstrator, but the guy was unsure how many were built.