Played with controlled intensity by Edward Woodward, David Callan is a working-class loner, reluctantly yet ruthlessly stitching up or shutting up Eastern Bloc agents, ex-Nazis and possible security risks, all at the behest of a murky section of British intelligence. "All the rotten jobs," as he puts it.
With just three TV channels to choose from, an evening's viewing in the late 1960s was somewhat limited. But even if there had been more, Callan would still have led the field: in a time before video recorders, this seminal spy series from ITV – with its iconic swinging-lightbulb title sequence, its sharp scripts and cracking characters – was stay-in TV.
The show turned the James Bond image on its head. Callan, possibly TV's first antihero, is the section's top killer,