nor did he seek advice from the queen

Jenny Hocking - Palace Letters is definitely a key source for these questions.

Kerr certainly sought a great deal of advice from the Queen through her private secretary Charteris.

Anthony Mason, and one other High court judge were certainly involved.

CIA, they might not have liked Whitlam, they mighy have expressed a specific interest in the happenings of an ally. But i don’t know if i’d even call that circumstantial evidence they were involved. The Americans could have been given a nod and a wink from Buckingham.

The key element here though, is Kerr pursued it for months and months contacting and almost obsessing over this unproven power. From what i’ve read, i can’t see that anyone but Kerr himself was the central driving force behind the sacking. The rest are certainly interested parties though, some like the High court justices i think acted treasonously.