British tourist Julie Stott (pictured) was killed in New Orleans

At first,' said Robert Jones, 'I thought this must be a practical joke. But the police were real, and they were taking me to the homicide division. I assumed they would turn me loose, because I'd done nothing wrong. Of course, that didn't happen.'

Jones, now 44, is describing his arrest at 4am on April 18, 1992, for the notorious killing of a British tourist, Julie Stott, as well as three robberies and a brutal rape.

He had no previous convictions, and by the time of his trial, another man had already been convicted of Julie's murder. But Jones was to spend the next 24 years of his life locked up in Louisiana's most terrifying prisons for crimes that even the lawyers who convicted him knew he had not committed.

It was not until the end of January this year that New Orleans prosecutors, who for years hid evidence proving Jones's innocence, finally announced they would not seek a retrial, following his victory on appeal.

Incredibly, the manhunt that led him to spend more than half his life in jail was backed by a British newspaper, The Sun. Having offered a $10,000 reward for information leading to the arrest of the man who killed Julie, who had been holidaying in New Orleans, it later boasted on its front page that it had 'trapped Julie's killer', adding that Jones was a 'beast' who was 'raised in a stinking hell'.

The British connection does not end there. Were it not for the dogged persistence of two British lawyers, Emily Maw and Richard Davis from the Innocence Project New Orleans (IPNO), then Jones would still be in the stinking hell of the Angola penitentiary, a former slave plantation where inmates still pick cotton in conditions little different from the 1850s.

This isn't just a story of a prisoner fitted up, wrongfully convicted and freed because of bombshell new evidence. It is also the story of a man of exceptional courage, who overcame impossible odds and utter degradation to prove his innocence and emerge as a man transformed.

Robert Jones spent 24 years locked up in Angola penitentiary (pictured) in Louisiana

When Jones went to jail, he could barely read. He left not only with a high school diploma, but having passed college-level law courses that meant he did much of the legal spadework that underpinned his appeal. Inside he also ran a prisoner self-help group with 700 members. 'I was supposed to die in prison and to stay the way I was: an uneducated black boy,' Jones said. 'I didn't let that happen. But I feel for Julie and the other victims. Like me, they are victims of a system that failed.'

Julie Stott, 27, a fashion graduate from Greater Manchester, was murdered on the evening of April 14, 1992 towards the end of a holiday with her boyfriend, Peter Ellis. They were walking to their hotel through the New Orleans French Quarter when a gunman leapt in front of them and told them to lie down. They were slow to comply, and the man fired. One bullet grazed Peter's shirt but Julie was hit twice: in the arm and, fatally, in the head.

It was soon apparent that the murder was one of a series of attacks. Witnesses said the perpetrator drove a distinctive vehicle – a maroon Oldsmobile Delta 88 with a white roof. Six days before the murder, its driver had robbed and kidnapped a woman, whom he raped several times. The same man was believed responsible for a further robbery shortly before Julie was murdered, and yet another one afterwards. The police had no idea who he was.

Enter The Sun. Julie's slaying triggered outrage in Britain, prompting the paper to offer the reward – which in fact, was never paid. But to the poor black community of New Orleans, $10,000 was a fortune. Calls flooded in to police, and somebody fingered Robert. Arrested while in bed with his girlfriend Kendra, he was paraded half-naked in front of the TV cameras, and charged later that day.

Robert Jones was taken to the Orleans parish jail, 'a dangerous, violent place, full of drug addicts who were detoxifying', he says, and was locked in a four-bunk cell. 'There were fights all the time, often over food.'

In the following months, he sustained several injuries: 'broken fingers; a broken wrist'. The jail was filthy and anarchic: 'The guards were in control, but they left a lot to the prisoners.' Two weeks after his arrest, Kendra paid her first visit. She had big news: she was pregnant. 'I was excited and sad, all at the same time,' Jones said. 'Until I went to jail, I didn't have an idea that innocent guys could be convicted. But now, everyone was telling me: it happened.'

The figures bear him out: since 1991, 44 long-term and death row Louisiana prisoners have been exonerated, 18 of them thanks to IPNO.

Meanwhile, two days after Jones was arrested, a gunman held up another couple walking through New Orleans, ordered them to lie down and stole their jewellery. Then he drove off in a maroon Delta 88 with a white roof.

It was not until the end of January this year that New Orleans prosecutors finally announced they would not seek a retrial, following his victory on appeal (pictured, Robert Jones)

This time, the police, led by Detective James Stewart, traced the car and its owner, Lester Jones – no relation to Robert – to a run-down housing estate. He was wearing jewellery stolen in the robberies and from the rape victim, and more was found in the car, while a gun in his apartment was an exact ballistic match for the weapon used to murder Julie. Stewart hunted for evidence of a link between him and Robert, but found none. It should have been obvious that charging him had been a mistake. But the New Orleans District Attorney's office – led by Harry Connick, father of singer Harry Connick Jr – refused to admit it. Lester Jones was charged with the murder and the robberies, but Robert stayed in jail, still facing trial.

Lester's trial came first, in 1994. Julie's parents – both now deceased – attended, and he was convicted and sentenced to life. Two years later, Robert was tried. The hearing lasted just ten hours. The prosecutor claimed Lester Jones had told police he knew Robert, and that he had lent him his car so he could kidnap and rob the rape victim; supposedly, Robert gave him her stolen jewellery.

Robert was innocent of the rape and robberies, but the jury found him guilty, probably because the rape victim claimed she recognised him.

He was sentenced to life, and afterwards prosecutors offered a deal: if he pleaded guilty to Julie's manslaughter, he could avoid a murder trial and a second life sentence. His defence lawyer persuaded him to take it, and for this he got 20 years, with 25 years for the robberies.

Once convicted, he was taken to Angola. Most of its 5,000 inmates will never leave alive, because they are either on death row or serving life without parole. 'For the first few years, they had me working in the fields, growing and picking cotton,' Robert said. 'You've seen the old movies: a guard with a shotgun, a line of fieldhands, most of them African-American. That was the set up. It was totally degrading. When I got there I met guys who'd already been in for 30 or 40 years. Soon, two or three guys a month I knew were dying, from conditions like heart disease and cancer. I was determined to try to fight my way out.'

The low point came when his brother, Pierre, was killed in another senseless street attack. 'He was trying to raise money to get me a lawyer who would get me out of prison. That's when I started to give way to depression. But I decided that if I couldn't get a decent lawyer, I'd have to educate myself and find a way to do it. I got on all the education programmes. I passed my diploma and started studying law. In 2002, I wrote to IPNO.'

Emily Maw, 40, IPNO's director and a mother of two, was brought up near Bristol and has been fighting cases in New Orleans since 1999. Her colleague, Richard Davis, 34, is from Hertfordshire. Driving both is a simple desire to right injustice: 'It seemed right to do what we could to stop Robert dying in jail for crimes he hadn't committed,' Davis said.

Their first big hope was to DNA-test forensic samples taken by police from the rape victim – but in 2004 they were told that, mysteriously, these had 'disappeared'. Then, IPNO staff visited Lester Jones in prison. He swore an affidavit insisting he had never met Robert, that his claim he had done so had been beaten out of him by police, and that he had retracted it long before Robert's trial. But in 2007, having considered what Louisiana calls a post-conviction petition containing this and other new evidence, the court rejected it.

Over the next few years, Maw and Davis spent thousands of hours on Jones's case. Meanwhile, his own situation improved. 'I'd left the cotton fields. I worked on industrial jobs, then in vocational training.' Before his daughter with Kendra, he already had two children, and he worked hard to foster relationships with all of them, through visits, letters and phone calls. 'I knew the statistics. If you're a child with a father in prison, you're likely to follow them. I did what I could not to let that happen, and they're all OK.'

Proudly, he listed their jobs and accomplishments: one is a beautician and social worker; another a restaurant manager; the third divides her time between college and a supervisory hotel job.

From the moment IPNO filed Robert's last appeal until the prosecutors capitulated took almost seven years, with every step a bitter legal fight. But in the end, the evidence that he was framed was overwhelming.

Julie Stott's slaying triggered outrage in Britain, prompting The Sun to offer a reward – which was never paid

Maw and Davis obtained access to police files, and among their many discoveries was the fact both the robbery and the rape victims had initially described someone who looked nothing like Robert, but very like Lester. They also found conflicting statements from a witness who had claimed he saw an accomplice to Julie's killer rifling through her clothing as she was dying. He had been 'persuaded' to change his story: initially, he said he was certain only one man was involved. Sensationally, ex-detective Stewart came forward to testify, saying there was no link between the two men, and that he had always been sure one man committed all the crimes – Lester Jones.

But perhaps the most extraordinary discovery came last – after Robert's convictions were quashed, while the prosecutors were still considering a retrial. This was a 1996 memo by the trial prosecutor. This revealed he knew all along Lester had 'recanted' his claim to know Robert, and this left no reliable evidence that Robert was involved in Julie's murder. This was the true reason why prosecutors offered the manslaughter deal – because he knew if he did not plead guilty, 'such evidence would not survive appellate review'.

After the Louisiana Supreme Court rejected an appeal from the prosecution, Robert was released from Angola at the end of 2015. But it is only now he is truly free to pursue his dreams of a stable life, and of going into business as a real estate entrepreneur: 'I defied a system that was out to destroy me, and I lost a lot of years. But I also educated myself, interacted with a lot of great people, and that was a beautiful experience. Yet no one, in all these years, has ever said sorry. That's crazy, isn't it?'