When John Humble was shaken awake on a cold morning in 2006 by officers entering the cell he’d spent the night in, it took some insistent persuasion to convince the arrested man where he actually was. Humble, 50, was in a police station in West Yorkshire. He was 100 miles from the shabby, semi-detached house he shared with his brother Henry in Sunderland and it has been 27 years since he wrote the letters that became known as the biggest red herrings in British criminal history, all part of a story about to be dramatised in The Long Shadow, a new seven-part ITV series starring Mark Stobbart, Toby Jones and Daniel Mays.

His journey across county boundaries from Northumbria to Yorkshire was the farthest Humble had travelled in many years. To the residents of Flodden Road on the Ford Estate in Sunderland, Humble was known to go no further than the corner shop where, each morning, he could be seen lurching along the streets clutching carrier bags full of Lambrusco, lager and cheap cider.

Locals saw Humble as a harmless, alcoholic loser. Kids on the estate saw him as fair bait; shouting abuse at his stooped figure while some even attempted to pickpocket Humble as he shuffled along the pavement. What the residents didn’t know was that Humble’s mediocre, aimless life, saturated in alcohol, was partly the result of the guilt he had been carrying for over a quarter of a century which now, as he sobered up on a chilly morning inside a Yorkshire prison cell, was coming back to bite him.

The Yorkshire Ripper case was, by this point, considered a fading nightmare by those who lived through the hellish years of the mid- to late-1970s when a serial killer targeting women roamed the parks and streets of Bradford, Manchester and Leeds. In 1981 Peter Sutcliffe, a lorry driver from Bradford, had been convicted of 13 murders and confined to Broadmoor on a life sentence. Case closed.

But a cold case review was about to reveal the identity of ‘Wearside Jack’: a hoaxer whose spate of cassette tapes and letters claiming to be from the Yorkshire Ripper sent West Yorkshire Police on a wild goose chase, allowing the real Ripper to stay on the street and clock up more murders in the interim.

In the 1970s, a 22-year-old Humble, having failed at nascent attempts to forge a career in labouring, was spending his days in Sunderland’s Kayall Road library, where he became fascinated with the 1888 case of Jack the Ripper and the horrific spate of murders in Victorian Whitechapel.

Sitting in his mother’s kitchen in Sunderland, unemployed and bored, Humble began to create a series of anonymous letters and a cassette tape with a spoken word message addressing George Oldfield, the lead officer on the Yorkshire Ripper investigation, claiming that he was the man the police were looking for.

The ruse worked more spectacularly than Humble may have ever expected – or wanted. Oldfield and the Ripper team believed that the letters from ‘Wearside Jack’ (as he became known due to his accent on the tape) had to be genuine as they contained details about Jean Harrison, a murder victim suspected to have been killed by the Ripper, that only the killer could have known.

This was an error. It would later emerge that every detail mentioned by Humble about the Harrison murder (who was not, it was later discovered, killed by Sutcliffe) in the letters had been previously published in local and national newspapers. While Humble’s letters, claiming that Assistant Chief Constable Oldfield should ‘warn whores to keep off streets ‘cause I feel it coming on again’, succeeded in putting police off the scent, the real Ripper kept on killing, claiming three more women’s lives before finally being arrested, initially for having false number plates on his car, in Sheffield’s red light district in January 1981.

Police, during the latter years of the hunt, were told to dismiss any suspect who didn’t have a Wearside or Geordie accent. Sutcliffe, hailing from Yorkshire, had no such accent and so, despite being interviewed nine times by officers, was allowed to walk free each time.

Amid Sutcliffe’s Old Bailey trial, and the subsequent winding down of the hunt, the story of the hoaxer was all but forgotten. It had potentially set Sutcliffe’s arrest back by years and had humiliated Oldfield who, having been convinced of the authenticity of the tapes and letters, retired early and died in 1985 aged just 61.

Humble had, it later transpired, attempted to come clean while the real Ripper was still at large. Phoning the Sunderland incident room from a pay phone, he repeated that the letters and the tape were all a hoax before hanging up. He wasn’t believed, and soon after, he attempted to take his own life by throwing himself off the 80-foot-high Wearmouth bridge. Humble’s fall was broken by a passing boat and he was dragged to safety by police officers entirely unsuspecting of his hoax.

Despite the weight of his guilt, Humble will never again get to the point of confessing. Instead, his descent into alcoholism continued for over a quarter of a century, until 2005, when his addiction to the bottle led directly to his identity being revealed. As part of the cold case review, the DNA from the envelope seals of the ‘Wearside Jack’ letters was placed on the police’s national DNA database. A match was found between the envelope sample and a saliva swab Humble had given after being arrested for being drunk and disorderly in the intervening decades.

As his drink-addled brain began to comprehend what was happening to him in the police interview room in 2006, Humble initially denied being the hoax letter writer. He finally confessed after being told that the DNA connection meant that the chances of the letter writer not being him were around a billion to one.

His lawyer argued in court that Humble’s letters and tapes didn’t amount to perverting the course of justice and that he was guilty of nothing more than wasting police time. The judge disagreed, sentencing Humble, now in his 50s, to eight years in prison. Humble’s sole motivation appears to have been boredom. “It was a stupid thing to do,” he said at the time, “and I’ve regretted it ever since.” He was released on licence in 2009 having served only half his sentence.

With a new identity as John Anderson given to him by police, Humble retreated to the small town of South Shields where his drinking increased until, on 30 July 2019, he died at his home from heart failure aged 63.

When Peter Sutcliffe was convicted in 1981, judge Mr Justice Boreham told the court, “The scent was falsified by a cynical, almost inhuman, hoaxer – I refer to the tape and letters. I express the hope that one day he may be exposed.” Years later the now-retired Detective Chief Superintendent Chris Gregg, who was part of both the initial Ripper murder investigation team and the cold case review which finally caught Humble, went on record as stating that the original manhunt was ‘derailed’ by Humble’s letters and tape recordings.

Humble was exposed. But it took 27 years for the voice of ‘Wearside Jack’ to be brought to justice for his role in helping to prolong the killing spree of one of Britain’s most monstrous serial killers.

The Long Shadow premieres on ITVX on 13 September 2023.

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