Just popping in to say that I've now watched the first six episodes of series 4.
(Don't worry, izzy, I'm not going to reveal any plot developments you're not up to yet!
Verdict: It's wonderful! I'm addicted.
What a terrific cast, what fabulous scripts, what terrific filming!
I suspect there are quite a few local details & subtleties that you US folk might understand that I might not have picked up 100% ....
But what the heck.
This is wonderful stuff.