 The main character Barlow originated in _"Z Cars" (1962)_ (qv) and  then moved over to _"Softly Softly" (1966)_ (qv) before this series.  He also appeared in _"Jack the Ripper" (1973)_ (qv) and  _"Second Verdict" (1976)_ (qv) where Barlow and Watt examined real  crime cases.