The rough, tough and downright dirty world of New Scotland Yard's heavy mob - The Sweeney.
So-called because the Cockney rhyming slang for Flying Squad is The Sweeney (Sweeney Todd -- famous murderous London barber -- Flying Squad). The term "flying" because they came on the scene quickly after bank robberies or other "serious" crimes.
It doesn't get much better than this. It really doesn't. Around 1975 we didn't have video recorders so you made sure that you were sat down with your coffee for the ITV 9pm showing! The show's genus is in the acting and script -- as well as the real locations of South London. Tatty high rises, breakers yards (ideal for fighting!), smoky clubs/pubs and "the factory" the office that they worked from with its grey walls, round dial phones and worn out office equipment.
(This was actually modelled on the real Flying Squad office!)
Occasionally this would contrast with the middle class splendour of the super villain or mastermind who planned the central crime like a chess game.
John Thaw (as Jack Regan) was a genius of an actor, but always a tough guy at heart. Even when he put on a posh accent. In his younger days he was a bit of a bully and a tearaway, being a kind of "king of the teds" character. How he ever got in to acting is a long and unlikely story.
(I won't bore you with it.)
Dennis Waterman (as George Carter) was originally going to be only an occasional character and the whole show was going to focus on Regan - but the writers noticed that they made a team and the script was changed. The final line in the triangle was the (mostly) office bound Garfield Morgan (as Chief Insp. Frank Haskins) ) who was the voice of the reason that generally wanted "to go by the book."
(Regan never wanted to go by the book -- he "wanted results" any way he could get them!)
As the series progressed it got more adventurous and sometimes things went badly wrong. There was sometimes odd-ball comedy episodes. Unlike any other cop show before or since it was suggested that some of the criminals were behind bars for things they didn't do -- and the methods of Regan himself were bound to get him in to serious trouble (with the "brass") sooner rather than later.
Naturally The Sweeney did have its limits. Regan rarely was on the wrong track (even when evidence pointed another way - he always "had a hunch") and rarely did the cons lay down their weapons readily. Which I am sure they would in real life -- especially when the police had attack dogs and guns. It wasn't a show that was in full flight from a cheap thrill.
This show went all around Europe (I saw one episode in Spanish) but I doubt it would do well in America. Too sour and not enough happy endings.Happy memories which were not bountiful in the 1970's.