to September 16, 1950. Prince George Valdemar of Denmark (eldest son of Prince Axel) married Anne, Viscountess Anson, daughter of the Hon. John Bowes-Lyon and Hon. Fenella Hepburn-Stuart-Forbes-Trefusis (yes, THOSE Bowes Lyons. Anne was a first cousin of Queen Elizabeth II). The ceremony at Glamis Castle saw the bride in a most wonderful calot hat with curled feather trim.
Images from Getty as indicated
Royal Hats 
I love this look. Second time brides nowadays often choose the full white gown and veil again, but I like this option of a lovely coloured gown and a fancy hat. Do we know what colour it was?
Looks like the calot could be fur? In any case, I agree with LesleyC19 that it’s a lovely look for a second wedding. What an elegant couple.
I zoomed in on the photo to study the texture of the calot and I think it is made of feathers with those different and longer curled feathers framing her face. I am lacking in expert knowledge about feathers but the texture reminds me of a hat worn by Queen Elizabeth in the early 1950s that was similar. I must also say that the texture and weave of the fabric used for this dress is exceptional. I would dearly love to know more about this garment. The design is beautiful.
I found more information about what this hat might have been. Go to the website vintagefashionguild . org / hat-resource / casque
There is a photo of a 1950s Ranleigh feather casque that might be very similar to this hat worn by Anne. It has the correct silhouette (minus the curled side feathers) and textured look to the cap. If nothing else, its from the same time/era and we all know how current fashion trends influence other designers.
Love this hat and would love to know more about the brooch. The whole outfit is quite beautiful for a second wedding.