Many thanks Vincent. I agree with you, that Queen Mary is wearing the bandeau which she used for the large sapphire brooch and the Ladies of India carved emerald brooch -- it it the tiara I refer to as the "wing tiara"

I suspect that the photo might have been taken at the same session as the photo below, as the sleeves and, more importantly, the pattern of the embroidery of the beading are the same on both dresses. It would be a simple matter for HM to change necklaces and earrings but a more complicated matter to change a tiara with the hair style Queen Mary favoured.





Comparison of dress from the two photos.



As a non-tiara wearer I was fascinated to read Vincent's insights into the differences in how tiaras are shaped (constructed), and the significance of hair styles. Thank you Vincent!