When Hopkins was asked why he didn’t expose the plot earlier or refuse the job at the time, he explained: "MI5 agents swear allegiance to the Crown," "We can’t be impartial when it comes to the Royal family." "At best I would have been done for treason, at worst Philip would have designed a grisly fate for me."
http://www.neonnettle.com/news/2293-...bed-confession

What wasn't mentioned was her dating and possibly engaged to Dodi Fayed, a rich muslim as well as being pregnant. You can see why the crown may take a dim view to a princess marrying a woggy.

Wog aka wile oriental gentleman