Thanks for the response, but that's not quite that for me. I'd gone to Ashweald and Bleden Mark had pledged his allegiance to me before I went to Tunon's Court...
So order of events:
Go to Ashweald and speak to Bleden Mark, then proceed to Cacophony to kill the Archon of Secrets, then to Iron Hearth and kill the Archon of War.
Return to Ashweald, speak to Bleden Mark again, getting his pledge of allegiance and the power boost from that.
Then going to Tunon's court, having the run of dialogue. Bleden Mark appears behind you and takes part in the dialogue. Tunon declares me innocent, then invites me to talk to him.
I go up that area, you get Tunon's pledge of alliegiance. You have that scripted sequence of fatebinders, guards and such kneeling to you. Then they all go.
Left standing next to that throne with Tunon on his own and being unable to talk to him. The courtroom with the Fatebinders doing the same conversation options as before.
The world map has nearly all sights greyed out, just Tunon's Court, the various Spires, hm, and Halfgate and the Oldwall Breachs as locations I can travel to.
There are no fresh additions to the quest log - However, the Final Hunt quest still shows in the active list, even though all parts of it have been greyed out as completed.