The Touch of Frost series are outstanding. In particular, the interplay between Jack Frost (David Jason) and his boss "Horn-rimmed Harry" are brilliantly observed and often very funny. There is usually an interesting relationship with his sidekick, who changes with each episode. One of the best things about the programme is the way it doesn't patronise the viewer: the characters, especially Frost, are shown as very imperfect. It's also not afraid to end on a melancholy note; Frost, after all, is something of a tragic figure.
I've seen 2nd and 3rd repeats of these, and they're still enjoyable, which is saying something for TV films. Jason is a superb actor, best known for a comedy in the UK (Only Fools and Horses) rather than serious drama, and his comedy touch is superb.
For anybody who delights in engrossing stories and exquisite human characterisation rather than standard police show cliches, Touch of Frost is exceptional. I can't recommend it highly enough.