In the season 6 finale,
we see barrels of wildfire ignited under the Great Sept of Baelor, where the Faith were holding Cersi's trial, killing everyone inside.
I'm slightly confused as to how many characters were involved in this. Specifically:
Were some of the Faith Militant involved, as when
Lancel went following the child that later stabbed him,
none of them went to fetch Cersei.
Further evidence that some of the Faith were involved, is that they stopped everybody from escaping the building, including Margery. However, this could have just been them trying to rein everybody in and keep things under control.
Additionally, how did Cersei get the candle all set up and ready to set off a chain reaction- and at the right time? Did she receive aid from Maester Qyburn?
So to summarise, what characters had some involvement in the Destruction of the Great Sept of Baelor, and were there specific hints of this approaching in previous episodes?