Series where everything changed?

[SweetTea]

I just finished a re-watch of Series 5 and what I noticed was that in almost every episode there is someone from within the government that is either working against them or out-right screwing them over. Here's a list:

Episode 1 & 2: Michael Collingwood, MI-6
Episode 3: No one
Episode 4: James Allen, Foreign Secretary
Episode 5: Oliver Mace, Chairman of the JIC
Episode 6 & 7: Neil Sternin, MI-6
Episode 8: Charles Lee, chief legal counsel for Downing Street
Episode 9: John Russell, MI-6
Episode 10: Janet Wheeler, Science Advisor to the PM

I haven't been making notes on other series as to how often the foe is someone from within, but it really struck me with this series. Now I'm curious enough that I want to go back and remind myself of how much this happened in the other series.