Geoff
The identification is to do with the shape of the yellow gap. I have sent you some photos of both Great and Temmincks which highlights the differences.
Basically on Great the yellow gap goes straight down where as on Temmincks it angled.
Its hard to tell from your photo but I would er on the side of Great
If you look at the old BB there is a very good thread on how to tell the difference
HK Twitcher