This really is a fine series overall.
The format is standard (Scotland Yard CID called into assist cases that are two difficult or sensitive for the local force) but here is done without screaming car chases and big budgets; more Jack Hawkins than the Sweeney.
The central characters Chief Supt Kingdom and Inspector Ward are well characterized by John Woodvine and John Carlisle. The interplay between them and their fathoming of cases is very subtly done.
Ward's character is perhaps the more interesting but inconsistent. He starts off as stridently anti-authoritarian, but then becomes a mixture of cynical, whimsical, and villain-hater. Each version is well played by Carlilse but there was obviously a struggle in the script editing dept to find quite the right version of the character.
Woodvine as Kingdom is also very good on the detection but weaker when it comes to his home life; attempts to portray angst in his marriage get a bit bogged down and leaden but thankfully there isn't too much of that and the focus is firmly on solving crimes.
Being from the early 70s there is a glorious lack of "background" music so one can enjoy the drama without being aurally assaulted as in most modern stuff.
Apart from the characterisation the main strength is the variety of interesting cases in which the detectives have to ponder a wide range of people and motives.
As others have mentioned, things drop in Series 4 when Carlisle and Woodvine are replaced. The stories are still good but the loss of the two main performances does create a disappointing hole. Presumably Woodvine and Carlisle saw the writing on the wall as series 4 is shorter than the rest and executives at LWT and Thames were no doubt looking for more action-based, bigger budget stuff with the Sweeney in the offing. Still it had a good run - 3.5 series is quite an achievement for a prime-time series.
If you like interesting, cerebral crime-solving, you will enjoy this.
