Great sleuthing Ruth! Most of Diana's hats were by John Boyd in the early years... Those in the photos are pretty typical, so that may well be. I've never seen the third picture so I couldn't say. Who knows... the interesting thing also is, which no one else seems to have noticed is that the white wide collar doesn't seem to have been a part of the green dress, rather it was a separate blouse with that collar that she wore underneath the dress. Because the collar crops up again in another pic, with a pink dress, and there one can see that it must have been a separate blouse she wore under the dress. So maybe the dress was by one designer and the blouse by another. My books aren't any clearer about this. Both of them appeared after her death, and I think they relied on info from either the designers, other people that were close to her and probably press records. But even at the time they were written, that was already over 10 years in the past.
Karin