The cop drama that rewrote TV history

G F Newman's Law and Order shocked the nation when it was shown on television 31 years ago. Its first airing since will still pack a punch, says Gerard Gilbert

Take two British television dramas about police corruption and brutality in the 1970s. Channel 4's Red Riding, which finished last week, attracted almost universal praise for its drama, but barely raised an eyebrow with its graphic depiction of a named constabulary (the West Yorkshire Police) routinely torturing and murdering people. The BBC's Law and Order (not to be confused with the later US show, and its current ITV spin-off) depicted bent Seventies coppers and a violent prison service. Unlike the retro-saga Red Riding – or, for that matter, Life on Mars – G F Newman's Law and Order was broadcast to an aghast nation in the year it depicted – 1978. It was shockingly contemporaneous, in other words, and caused an uproar.

"There was a huge outcry from the police and prison service, and there were questions asked in Parliament," says Newman, who was later to create Judge John Deed. "Sir Ian Trethowan, who was director-general of the BBC at the time, was summoned to the Home Office by John Harris [later Lord Harris], the then Minister of State in the Labour government. I was told by a civil servant who was present that he was read the riot act and was told that this was not the sort of programming that was wanted on the BBC and it wasn't to be sold abroad so as not to promote such an image of Britain.

"I was also told that Trethowan was quite bold in the defence of it – not that he had any particular liking for the show, but that he felt that the BBC shouldn't be dictated to by a minister. Nevertheless, he clearly was influenced, because it never did the see the light of day again."

Not until now, that is, for the BBC is about to screen Law and Order for the first time since its unofficial prohibition 31 years ago. The quartet of dramas, which looked at the judicial system from the viewpoint of the police, the criminal, the barrister and the prisoner, are to be screened on BBC4, starting tonight with A Detective's Tale.

Derek Martin, known these days for playing Charlie Slater in EastEnders, posted the performance of a lifetime as the hooded-eyed and thoroughly rotten apple, Detective Inspector Fred Pyle. Fitting up innocent suspects and taking back-handers from villains, Pyle was based on the stories told to Newman by the real-life policemen he had befriended while writing a 1970 novel about corruption, Sir, You Bastard.

"I knew a couple of detectives," he says. "And through them I would meet other detectives and seemed to be accepted within that circle. Despite Sir, You Bastard, there was no loss of friendship. I suppose they saw that I wasn't blowing the whistle on any individual, just the institution. And anyway I think they felt so confident within their corruption that they were untouchable. So the friendship continued, and through them I also met criminals and criminal barristers."

Another future EastEnders regular, Peter Dean – he was to play Ian Beale's dad, Pete – portrays Jack Lynn, the career villain at the centre of A Villain's Tale, set up by DI Pyle for a robbery he didn't commit, because "it was his turn". We meet Lynn again in A Prisoner's Tale, a damning exposé of the penal system, while an unusually restrained Ken Campbell plays the defence lawyer in A Brief's Tale.

I recently watched the four episodes – each of them is 90 minutes long – and was utterly transfixed. Certain things are inevitably dated – the typewriters, the cars (they even sounded different back then), the lack of policewomen (other than secretaries) and the lingo ("nice whisper from a snout of mine – there's a lad that's a bit active"). But these are far less distracting than the undeniably beautiful and painstaking period detail of Red Riding. A substantial part of Law and Order's power – now and then – emanates from its low-key, pared-down realism, the series having been credited for creating a whole new type of drama dubbed "faction". Admittedly it might seem a bit slow to modern sensibilities – but I couldn't detect an ounce of narrative flab.

During the shoot, Newman found some novel ways of keeping it real, including taking set designers on an after-hours visit to New Scotland Yard, and having Met officers return the favour. "We had cops down on set – showing actors how to behave, how to rough people up." He also claims to have bunged the policemen tenners to pretend to arrest the set designers, so they could get to know first-hand the places through which an arrested person would be processed.

In any case, Newman, and director Les Blair, have crafted a drama that stands the test of time. And it had to, thanks to its three decades on an unofficial blacklist. "There were things that have been clearly and publicly banned, like Dennis Potter's Brimstone and Treacle and Scum," says Newman. "But ours was never openly banned. But we couldn't even get it out to show it at festivals.

"And I remember about 16 years ago a producer at the BBC rang me and asked whether she could get the rights – in those days as the writer we still retained the rights to the words – as she wanted to show it as the centrepiece of a season called Cops on the Box. I said, 'Are you sure about this?' and was told, 'We'll call you nearer the time'. But the call never came, although the Cops on the Box season came and went. I rang to ask what had happened. 'Oh no,' she said, 'we didn't think it was relevant'."

In the meantime, Newman discovered that the series had an influential admirer in the States – the film-maker Michael Mann. "I got to know Michael after he asked me to write a screenplay about the American Revolution – the film that became The Last of the Mohicans. I was about to make my directorial debut in television and said I couldn't do it because I was doing something else. And then the something else didn't happen."

Mann tried to get Law and Order remade for American television, but to no avail. In the meantime he regularly screened it on the set of Miami Vice – something that was later to give rise to suggestions of plagiarism when Dick Wolf – then a supervising producer on Miami Vice – eventually sold a series by the same name to NBC: the globally syndicated smash hit Law & Order.

Although the format of Wolf's Law & Order is almost identical to a 1960s series called Arrest and Trial, Newman believes there are also similarities to his drama. Did he think Wolf had nabbed his idea? "Michael Mann certainly took that view," says Newman. "He phoned me up and said, 'You've got to sue Dick Wolf'. I was in the middle of a plagiarism case at the time. Fortunately we won, but I didn't fancy the prospect of going into another piece of litigation."

When Newman finally did find the stomach for a fight, he learnt that he had run out of time under the statute of limitations. "I can see the argument for a case," he says now. "But I can't pretend that I've been eaten up by it over the past 30 years. By the way, as a piece of thumbnail arithmetic I would be owed about $300m in royalties."

Poorer, in theory, but unbowed, he is currently working on updating his Law and Order, although he says it would be hard to call it that now because of the Dick Wolf version. "There is still police corruption, but it's a different sort of corruption now – it's a kind of bureaucratic corruption. Everything is done by computers now, and there are ... well ... shall we say 'mistakes' made on computers. But I won't go into that because that's the basis of my new episodes."

He still has his police contacts. "The generation of policemen I knew when I started have all retired, of course – over the years you got passed on, as it were, to their sons, and friends of their sons." Does he retain his oft-stated belief – and the premise behind Law and Order – that the person who becomes a policeman has almost exactly the same pathology as the criminal?

"I don't think the nature of people attracted to policing has changed. But I think the checks and balances have got harsher, so they're not left to their own devices entirely any more. They used to be left entirely to their own devices. I think any institution like the police left to their own devices unchecked will avail themselves of corrupt opportunities."

What has changed, he believes, is the nature of the people working in television – one reason he thinks his new drama may face difficulties getting commissioned. "They aren't radicalised or politicised as they were in the Seventies. Television is very cyclical, though; the wheel will turn."

'Law and Order' starts tonight on BBC4 at 10.50pm