Ah, I don't think this is Riihimäki... I saw one today in amber, with it's original 6 glasses, the spout isn't quite right, the glass was too thin, and the glasses that came with it were the wrong shape from genuine Nanny Still ones.
It's an intriguing one, isn't it? When you say the glass was thin, how thin, because I wouldn't say the green one is particularly so. Also, did the spout differ in a deliberate way?
Having looked through the pictures I've access too, there are some subtle differences between all of them—for example, the general inclination of the spout—which I suppose could be due to production inconsistencies.
On the green one and Pip's turquoise one the inclination of the spout looks less than on yours and that reproduced in "Nanny Still: 45 Years of Design", and the one in the 50s Finnish glass catalogues reprint book, resulting in a tighter curvature to the underside. However, the handle on Pip's, is more like the catalogue one, with the lower part nearly horizontal, whereas yours and mine are more inclined.
I'll take more photos of the green one tomorrow for you to look at, so you can compare with the amber one and your turquoise example.
Here's another one where the spout looks different again, and the handle is more like that in "Nanny Still: 45 years of Design":http://pettueerikki.tripod.com/keremiikka/index.album?i=13
As we know, it's quite possible that another company made something very similar, maybe including my green one :lol: (thinking here of your Holmegaard "Copenhagen" / Maleras thread)