Prince Philip would be wearing the breast star or The Order of Charles III and his Garter star. It is hard to see in most of the photos but a bit easier is you watch a video of the Royal progression into the ballroom for the State Dinner.
Prince Charles wears his star of the Order of Charles III and his Garter star.
The Duke of Cambridge wears his Garter and Thistle stars.
Prince Harry wears his star of the Order of Isabella the Catholic and his star of the Royal Victorian Order.
You can also see a quick glimpse of The Duke of York wearing two stars - most likely the Order of Isabella the Catholic and his Garter star.
I am having trouble with The Princess Royal. I am pretty sure that she is wearing the star of the Order of Isabella the Catholic at the state Dinner, but I am not sure if she is wearing her Garter star.
Surprisingly, at the Guildhall dinner the next night, The Princess Royal is wearing her Garter sash and the star of the Order of Isabella the Catholic but NOT her Garter star. Perhaps it is too uncomfortable with all of those pointy stars??!!
Here is a link is PP at a previous Spanish stare visit
https://www.google.com/imgres?imgur...5_VAhVLwYMKHRQVBIkQMwgnKAAwAA&iact=mrc&uact=8
Here is The Princess Royal at the Guildhall