While Princess Diana may have married into the royal family, it turns out her lineage was impressive even prior to her marriage to Prince Charles. In fact, her family is related to many prominent people in history.
Princess Diana, from the Spencer family, is actually one of the most distinguished aristocratic families in the United Kingdom. According to the Cheat Sheet, the Spencer family dates back to the 15th century and contains many prominent figures.
Of interest, though, is her connection to English Prime Minister Winston Churchill who led the country to victory during World War II. He held his position as prime minister from 1940 to 1945 and 1951 to 1955. While this is an impressive feat, Churchill was also a statesman, writer, and army officer during his lifetime.
And, according to the Spencer lineage, Diana and Winston Churchill are also distant cousins. Both Diana and Churchill are believed to share the same relative. Charles Spencer (1675-1722) was the third Earl of Sunderland and married Lady Anne Spencer (nee Churchill). It is believed that this couple was Winston Churchill's great-great-great-great-great-grandparents. In addition, they were also Princess Diana's great-great-great-great-great-great-great-grandparents.
But how did Winston end up with the Churchill surname if his great-great-great-great-great-grandmother dropped the name upon her marriage to Charles Spencer?
As Cheat Sheet points out, Churchill's great-grandfather, George Spencer, the 5th Duke of Marlborough, "added Churchill to his name in 1817 to highlight his family's history and add the connection to his prominent great-great-grandfather." So, the name became hyphenated as Churchill-Spencer.
In fact, this hyphenation of the two names still exists today. However, Winston Churchill decided to drop the addition of Spencer and just retain the Churchill surname. And, apparently, this habit is somewhat common within the Churchill-Spencer branch of the family tree, with other members of the family also choosing, on occasion, to drop a part of the hyphenated name.
George Churchill-Spencer also changed the family coat of arms with the addition of the hyphenated name. With the name change, the two family names' coat of arms were amalgamated to create a new, joint coat of arms.
Even with Diana's impressive family tree, she was still, technically, considered a commoner before her wedding to Prince Charles. However, this didn't mean she didn't uphold her own family traditions on her wedding day. At the time, Diana refused the offer made by Queen Elizabeth II to wear the royal tiara. Instead, she chose to honor her family by wearing the Spencer tiara. This tiara is worn by all Spencer brides -- including those marrying into the Spencer family.