Was princess Diana a princess only by marriage or was she related to a royal family?

Question

Why was she picked to marry prince Charles?

Answer 1

There was a distant relationship.  Very inbred: royalty and nobility.

Answer 2

Dianna's stepgrandmother was friends with the Queen Mother (deceased mother of Queen Elizabeth the second).  They introduced them or played matchmaker.  There was a lot of pressure on them to get married even though both had misgivings before the big day.

Dianna is a descendant of King William, the Conqueror.  Fifteen generations back Dianna and Charles are related directly to that same or common ancestor.  She was only a princess by marriage.  Before marrying Charles she was Lady Diana Spencer.

Answer 3

As Alletery says - a Princess by marriage.

I think she was also chosen to try to bring some looks into the royal family - who run to horse-faced women and jug-eared men. It worked, as William shows.

Answer 4

She was a princess only by marriage, however, she and Prnce Charles were 7th cousins as they are both descended directly from James I and VI.

Answer 5

She married an English prince Regarding your second question maybe that should be directed to Buckingham Palace ?

Answer 6

Lady Diana Spencer was a princess by marriage only, even though she was distantly related to the Windsors through an illegitimate liaison.  Charles is a descendant of James I (and the House of Stuart) through his daughter, Elizabeth of Bohemia, whose daughter, Sophia of Hanover, is an ancestor of all the Hanoverian kings who ruled the United Kingdom, the Saxe-Coburg Gotha family, and the contemporary Royals, the House of Windsor.  Diana, on the other hand, is a direct descendant of James I because Charles II's* first mistress, Lucy Walter, gave birth to James Croft, or James Scott, the Duke of Monmouth, whose descendants eventually married into the Spencer family.  All of which makes Lady Diana and Prince Charles very distant cousins.  Most of the aristocratic families of England and Scotland--and a large percentage of commoners as well--can make similar claims that link them to both past and present Royals.

Charles picked Lady Diana to be his princess because she was from an aristocratic family that socialized with the Royals and at age 19 presumably didn't have a past.  Diana's maternal grandmother was also a Lady-in-waiting to the Queen Mum.  Moreover, Camilla Parker Bowles assured Prince Charles that Diana was easily handled, meaning that he could resume his affair after she had produced the required heir and spare.  

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*Charles II was James I's grandson.