What if Cate was Philips daughter?
Then P = C makes sense.
There is no doubt Cate was bred for the job, her twin Mary, also married a future king.
https://www.dailymail.co.uk/femail/article-4908874/Times-Princess-Mary-Kate-Middleton-looked-twins.html
Ok, so the black horse was the City Of London surrendering to the King.
Charles now has complete control over England.
His enemies are dropping like flies, princess Mary and husband tried to flee to NZ, but were kicked out, and sent back to face the music.
My guess is Cate is the enemy.
Next to go will be Megan.