Series 10 Rumours & Speculation

[Silktie]

I think Erin is the new Section Chief, replacing Lucas. But this quote from that article:

But rest assured that good ol' Harry Pearce will still be the puppetmaster, even though secrets from his past threaten his role as MI5 chief.

sounds to me as though Harry is still operating in his normal role (as Section Head) whilst the problems brought about by the 'secret from his past' plays out around that.