The first series was Morse. They are all currently on Netflix. Oldest and I have both watched all (33 episodes, 8 seasons) of them. PBS and great (in our opinion).
When Morse stopped, Lewis (his sergeant) continued on PBS. Really great, maybe better than the original Morse, in my opinion. It is that series, Lewis, which is winding down now. The first seven seasons are free on Amazon Prime, for members. The last season, currently playing, is on PBS for free or Amazon Prime for a fee.
Meanwhile, a younger version of Morse, called Endeavor, started. The first two seasons are available free on Amazon Prime as part of their package. The third season is available for a fee. I happen to love Endeavor, but not everyone does.
Netflix = everything is free on their system for their members. Not everything is carried on Netflix, but if they have it, it is free for members.
Amazon Prime = somethings are free for members, other things require a fee. So instead of not carrying things, they carry them for a fee.
