At the start of the 1960s, viewers had two main choices of television cop show: the BBC's Dixon of Dock Green, whose hero was already 59 when the programme began in 1955; or ITV's No Hiding Place, in which Det Supt Lockhart, who wore his trilby at a rakish angle, righted wrongs and occasionally fluffed his lines.
On 2 January 1962, there was to be an alternative in the form of Z Cars, with little sense of reassurance or convenient plot resolutions via the last-minute deus ex machina of a senior officer sweeping up in his black Wolseley – just Ford Zephyrs patrolling a seemingly endless nocturnal vista of decaying warehouses and bleak new housing estates and shopping precincts.
In many of the storylines, police were ill-equipped or out of their depth dealing with crimes ranging from drink-driving to racial abuse.
Z Cars was devised partly because of the BBC's need for a drama to combat ITV's popular Emergency – Ward 10 and Coronation Street and to provide an alternative view of policing to that of the Dock Green police station.
One inspiration was the memoirs of former Det Supt Bill Prendergast of Liverpool City Police, whose experiences had already provided the basis for the 1961 series Jack and Knaves. Further input came from the scriptwriter, Troy Kennedy Martin, who had relieved boredom as he convalesced from mumps by tuning into the police radio channel.
The writer "occasionally came across incidents where it was obvious police were not coping", he recalled. "They seemed confused, lost, apparently young and inexperienced. The world that filtered through these fragmented calls was so different from that of Dixon that I took the idea for a new series to Elwyn Jones, who was then the head of a small but influential section of the BBC Drama Department." Research was undertaken with the aid of Lancashire Constabulary, whose chief constable, Col T E St Johnston, had recently supplanted constables on the beat with unmarked, rapid-response crime patrol cars crewed by two young PCs. This innovation would be the basis of Z Cars, set in the Northern town of Newtown, a fictionalised version of Kirkby, Merseyside.
When the chief constable saw a preview of the first episode, Four of a Kind, his force's support ended abruptly. Fifty years on, his wrath is fairly understandable.
A very unhappy Col St Johnston approached the Home Office and BBC in an attempt to have the series cancelled but viewing figures of almost 14 million prompted the Corporation to hastily extend the 13-week run to 31 episodes.
A surprising number of episodes from its heyday have survived, showcasing the writing of Alan Plater and John Hopkins and giving early roles to future stellar names, from John Thaw to Judi Dench.
Z Cars ran in its original live format for five series until That's The Way It Is, broadcast on 21 December 1965. When the show returned the following year it was as a twice-weekly soap opera and when the final episode was broadcast in 1978, it was only two years after George Dixon's overdue retirement.
But the impact of the early series cannot be underestimated. They were made at a time of headlines concerning the corrupt, violent and insane Sgt Challenor of the Metropolitan Police and the beating of suspects with rhino whips by the Sheffield constabulary.
The crews of Z Victors One and Two were merely overworked professionals policing an increasingly fragmented society in a world in which, in the words of the writer John McGrath, there were "no reassuring endings where decency and family life triumphed" – and where police were no longer seen as plaster saints but fallible human beings.