Referring to her as *Catherine* 

I was told in no uncertain terms that I could NOT refer to anyone, living or dead, by their 1st names on WP, & if a female had a title, she had to be referred to as that throughout her article - ie, *Lady Amy* or *Lady Dudley* for Amy Robsart, even though *Lady Amy* was wrong before she was married as she was the daughter of a knight & had no title, & wrong after Northumberland was attainted & all his children lost their styles as offspring of an earl & a duke, & she did not become *Lady Dudley* until Elizabeth I knighted Robert Dudley near the end of Amy's life nor was she then *Lady Amy Dudley* as legally she was no longer the wife of the son of an earl & duke.  I thought it was simpler to refer to her as just *Amy* throughout rather than explain the changes that occurred with her name & styles, but was told it was against WP *rules* (though I wasn't pointed to a link for it).  Noblewomen are usually called by their 1st names round here as far as I can see, even when they have surnames & are not *of* something!  Mary Boleyn is called *Mary*, not *Lady Carey* or *Lady Stafford*, Catherine Neville is called *Catherine* & not *the Duchess of Norfolk*, etc, & they're not royals.  

As for males, I was told they had to be referred to by their title - ie, *Leicester* -  or last name - ie, *Dudley*.  I was banging head on keyboard going, but - no one just says *the king* all the time or refers to them as *Plantagenet* or keeps changing their titles - ie, Henry of Bolingbroke going from Earl of Derby to Duke of Hereford to Duke of Lancaster to King of England -  

So how does Kate get to be consistently referred to as *Catherine* throughout the article, without her title appended?  I've only been here a few months & I would appreciate it if someone could actually explain this to me, as my main interest is British history & I am quite confused.