fifty-nine to January 21, 1961 when Queen Elizabeth and the Duke of Edinburgh arrived in New Delhi for a six week tour of India and Pakistan, the Queen in a memorably voluminous pale blue/grey tulle and silk flower trimmed turban.
Photos from Getty as indicated
Royal Hats 
HM wore this awesome ensemble in Pakistan later in the tour, and back in London upon her return home. Other than that, I found no other outings for it, which is quite a shame!
Lahore, Pakistan
March 10, 1961: Guilhall luncheon
Embed from Getty Images
I think the hat shows better in this video. Find the hat and whole ensemble just lovely, especially in the context of the visit, marked by many colorful flowers!
Wow, the pageantry! Thanks for posting, Beth. I’m not a fan of the hat, but the dress and coat are exquisite.
Though I am no expert on the style of the time, but that hat looks too large for the petite Queen.
I”m inclined to agree k2classroom, the hat seems unnecessarily large. However i do like how the hat’s texture plays against the smooth shine of the raw silk dress and coat.