Z-Cars further spin-off entitled "Second Verdict" in which Barlow and Watt looked into unsolved cases and unsafe convictions. Frank Windsor made a final appearance as Watt in the last episode of "Z-Cars", "Pressure", in September 1978, with Robins (John Phillips), the Detective Chief Superintendent from the original series who had risen to chief constable. Jeremy Kemp, Brian Blessed, Joseph Brady and Colin Welland also appeared, though not as their original characters. "Z-Cars" is incomplete in the archives. The period 1962–65 is reasonably well represented; though with big gaps. With the 1967–71 sixth series, when the programme was shown almost every week,
Z-Cars estates that had sprung up across Britain in the post-war years, and its ageing neighbour "Seaport". The stories revolve around pairs of officers patrolling that week. Riding on changing social attitudes and television, the social realism, with interesting stories, garnered popularity for "Z Cars". It was initially somewhat unpopular with real-life police, who disliked the sometimes unsympathetic characterisation of officers. Being set in the North of England helped give "Z Cars" a regional flavour when most BBC dramas were set in the south. It directly challenged the BBC's popular police drama "Dixon of Dock Green", which at that point had