Series 9 Episode 1 discussion

[HellsBells]

I have never understood this sudden change in the HS, as mentioned why on earth did the HS ever mention to Harry about Nightingale if he was part of it? Although it did allow for some great acting from PF. How did they find the link to the HS, in 8.8, the team didn't know who was part of Nightingale but within a week or so they uncovered the HS was a member of Nightingale.
It did seem to end far to quickly and easily, but I guess the writers wanted to get away from the previous writers ideas and run with their own.