If you're looking for any Princess Diana family history, Charles Spencer is definitely the best source. The younger brother of the late Princess of Wales is an accomplished historian and author, who always seems to be hunting down more pieces of his family's past.
Most recently, the 9th Earl Spencer dug up a photo of his and Princess Diana's great aunt, Lavinia. The photo was posted to Spencer's Instagram Story, where he said: “My great-aunt Lavinia Spencer, in fancy dress 119 years ago.”
The vintage snap shows a small Lavinia, around three or four years of age, standing in front of a door wearing a fancy white dress and bonnet.