Thank you Mauriz for those very interesting photos. I had completely missed them. I suspect that the two different tiaras worn by the brides in the two (but interconnected families) indicate which family owns which -- but, of course, I might be jumping to conclusions!
Thank you for that image The Royal Watcher. The tiara worn by Lady Alexander does indeed have some elements resembling the tiara worn by Lady Susan Hussey.
The date for the photos of Lady Mountbatten and Lady Alexandra and the separate one of Lady Mountbatten published by Getty is 2 July 1956.
For the dinner of the Canadian Women's Club in July 1956 Edwina Mountbatten, along with Lady Kilmuir, was a guest speaker.
There were usually two annual dinners: one for men and one for women. They were dining clubs, rather than official Commonwealth of Nations organisations, although no doubt the links were close.
The report I read said that, in 1956, the women's club was then 24 years old. The men's club, which held a separate dinner, was a lot older. It is an interesting reflection of how women were viewed at the time, and how women's organistions had started to assert the position of women.
The two photos from 1956 of Edwina Mountbatten. It is obvious from the dress and jewels that they are from the same event.
A separate news item after the death of Edwina Mountbatten shows one of the same photos. It was noted that the photo was from 1956.