Z Cars: The show that blew the whistle on the British bobby

At the beginning of the 1960s, viewers had two main choices of television cop show; the BBC's Dixon of Dock Green, whose eponymous hero was already aged 59 when the show commenced in 1955, or ITV's No Hiding Place, in which the hawk-like 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, in which there was 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, the police were either ill-equipped or hopelessly out of their depth when dealing with crimes ranging from drunk driving to racial abuse.

Z Cars was devised partially because of the BBC's need for a drama series to combat ITV's vastly 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 ex Detective Sergeant Bill Prendergast of the 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 during convalescing from mumps by tuning into the police radio channel.

The writer "...occasionally came across incidents where it was obvious that the police were not coping. 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 Colonel T E St Johnston had recently supplanted constables on the beat with unmarked, rapid-response "Crime Patrol" cars, which were crewed by two young PCs. This innovation would be the basis of Z Cars, which was to be set in the Northern overspill town of Newtown, a fictionalised version of Kirkby.

When the Chief Constable saw a preview of the first episode, "Four of a Kind", the support of his force ended abruptly – and 50 years on his wrath is fairly understandable. A very unhappy Colonel approached both the Home Office and the BBC in an attempt to have the series cancelled, but viewing figures of almost 14 million prompted the BBC to hastily extend Z Cars' 13-week run to 31 episodes.

A surprising number of episodes from the programme's 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 Z Cars 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 of Z Cars cannot be underestimated. It was made at a time of headlines concerning the activities of the corrupt, violent and insane Sgt Challenor of the London Met and the beating of suspects with rhino whips by members of Sheffield Constabulary. The crews of Z Victors One and Two were merely overworked professionals, policing an increasingly fragmented society in a world where, in the words of the writer John McGrath, there were "no reassuring endings, where decency and family life triumphed" – and where the police were no longer seen as plaster saints, but fallible human beings.