British Royalty Question: How did Camilla become Queen without ever being a Princess?

Queen Camilla at her husbands Coronation
Queen Camilla at her husband's Coronation

We Americans don't have Royalty (despite what the No Kings protests might imply) so we're not very good at understanding the rules.

I always thought that a woman was a Princess before becoming Queen, like Queen Elizabeth II was. Kate Middleton is Princess Katherine and will someday become Queen Consort when her husband William becomes King.

Yet, Camilla went straight from divorcée to Queen, and not even Queen Consort, never having been a Princess.

How did that happen? Did someone bend or break the rules?

Perhaps some of our UK members can explain this?

British Royalty Question: How did Camilla become Queen without ever being a Princess?
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