We binged this last weekend.
It's not an action series, and that's why the ratings are not as high as they should be. In my opinion it should be more lie 8/10. Many people see 'spy' and immediately think of Jason Bourne. This is not that at all. In fact it is mostly conversations and scenic shots of a wet and dreary Britain, Europe and the Carribean, and the story is about blackmail, politics and intelligence gathering. In any case there's all sorts of corruption being exposed and how greasy political appointments are managed. The main character is an experienced operative with a just-adult daughter, who he has to defend her sanity and honor in the 3rd episode (Spoilers - the other spooks use young gigolos to subvert her). It will appeal to those who like to see how all this stuff actually works. The second episode is hair-raising, in how close it matches world events.
Page Eight (2011), (Netflix) https://www.imdb.com/title/tt1797469/
Turks & Caicos, (2014) - has Wynona Ryder and Christopher Walken make appearances https://www.imdb.com/title/tt2904608/
Salting the Battlefield (2014) https://www.imdb.com/title/tt2904626/
One will need a handy gaming teenager to find these last two on a Pirate site (well we did, anyway).
Seen the first, and was impressed enough to seek out the others.