LightKo

No Littlefinger in the final ep? I don't see Aidan Gillen in the IMDb cast list for the episode. Maybe I'm missing something?

Why has Cersei summoned Littlefinger to KL? Is there any indication in the books of what this is about?

I take the accent shift to be tactical -- both on the part of the actor and the character. His more "refined" voice is a court voice, one used when talking to Lannisters, for example. His rougher accent (perhas closer to his natural cadance?) is coming through as he sheds his Kings Landing skin and now evolves into a new kind of snake.