Oh man, I could get lost here.
I revisited some favourites the other week.
Black Books that I think someone mentioned.
Killing Eve
Cracker (a bit dated now, but I lived where it was filmed and loved it)
Hustle (which I think Leverage was based on)
Spooks
Ripper Street (this is on Netflix)
Penny Dreadful (gothic girl crush on Eva Green)
Peaky Blinders
Black Mirror
Tales of the Unexpected (if you've never seen the originals... full of surprisingly famous people)
Morse, Taggart and any Miss Marple with Joan Hickson as Miss Marple
Poirot with David Suchet
The Adventures of Sherlock Holmes with Jeremy Brett (quite a few on YouTube)
Silent Witness (when I'm in the mood)
Dr Who (I was a Peter Davison child but I'd say that Christopher Eccleston deserved more than 1 series)
The Thick of it (Peter Capaldi's amazing as Tucker. I love every foul-mouthed word he says)
The Sarah Jane Adventures (a fun children's spin-off of Dr Who that's more light-hearted than Class and more in line with the original ethos of the show)
Torchwood (until the Americans spoiled it ie Series 4)
Sherlock, Luther, Broadchurch, Wallander, Dangerfield
Teachers
One Foot in The Grave
Blake's Seven (my all time favourite sci-fi show as a child, though the special effects and sets were terrible. The writing and acting more than made up for it.)
The Sweeny
The Professionals
The Darling Buds of May (Catherine Zeta Jones is v.young)
Larkrise to Candleford
Vera
Being Human (BBC version)
Merlin
I'll have to check it out. I'm almost done with New Tricks but, could watch the whole series again.
Right now, I'm watching The Suspicions of Mr Whicher. It's a BBC series of "movies". They're only an hour and a half. I'm assuming they aired on 2 consecutive days, for each "movie". There are 4 of them. It's very Sherlock Holmes. It's free on Prime right now. Worth a watch.
They probably just show them as a single 90-minute show rather than split them up. BBC shows tend to be 30, 60, 90 or 120 minutes, without commercial breaks so they often will air a 90 or 120-minute show int he popular before the news or just after the news slots.