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 longer format would still work. Thereafter, "Z Cars" was shown in alternating spells of either 2 x 25 minutes episodes or the single 50-minute episode each week over the next sixteen months. This arrangement ended with the showing of the final 2-parter, "Breakage" (Series 6, parts 74 and 75, on 21 and 22 August 1972 respectively), after which the series returned permanently to a regular pattern of one 50-minute episode per week. The "Z-Cars" theme tune was arranged by Fritz Spiegl and his then-wife, composer Bridget Fry, from the traditional Liverpool folk song "Johnny Todd". It was released on record