Donald Marshall and his cloning story should NOT be discounted, perhaps the 'Silent Scourge' after all.
Despite how the 'News' spun his tale, really explain 'HOW" a random, barely dressed 'civilian' managed to enter into the Queens actual bedroom and converse with her for over ten minutes before he allowed himself to be taken by the 'Royal Guards'.
https://www.ricksteves.com/watch-read-listen/read/articles/bedroom-window
Lillibet
I haven't found it yet, testimony to verify that Lilibet in fact collapsed at the 'cloning center' on the aforementioned night, but I will find it if it can be found.