I posted this picture last year I think. (from The Hulton Getty Picture Collection: The Queen Mother)
I also realized it's not the anniversary Lily brooch.(from Trevor Hall, The Queen Mother and her Family)
Today I found a picture on alamy.com that I believe maybe a match to the above picture. The pictures will be the original one and two close-ups. One of the close-up has been straighten the may the brooch is in the above photo..
But the more I look at the last three pics it my be the Anniversary Lily Brooch.. PJ