Colin Stagg comes face to face with psychologist who helped police set him up

Rachel Nickell’s murder shocked the nation; a young mother stabbed to death in a frenzied attack in broad daylight on Wimbledon Common in front of her two-year-old son. For years, Colin Stagg, an innocent man, was accused of the killing, set up to take the rap in a shameful "honeytrap" orchestrated by the Metropolitan Police.

Now 30 years on from the murder, Paul Britton, the forensic psychologist who assisted detectives in the inquiry, has finally come face to face with the man wrongly identified and vilified as her killer.

Their extraordinary meeting, filmed by documentary makers, shows two men who had been on opposite sides of the criminal investigation shaking hands. Mr Stagg tells Mr Britton that “it feels a bit strange” to finally be meeting the psychologist who had been involved in the highly criticised police investigation.

Mr Britton, 76, responds by way of explanation: “You must have heard some stories. You must have been told various yarns that end up giving you a particular way of seeing events… Well it caused both you and me some difficulty.”

Mr Britton said he wanted to meet Mr Stagg and break his silence, deciding that “it was time to put it straight”.

After the meeting, Mr Stagg, aged 59 and a registered carer, told the Telegraph he now saw the psychologist, once his adversary, as “more of a human being”. But he lamented the fact that Mr Britton had taken so long to jump to his defence after years of being wrongly under suspicion. Mr Britton explained that he had been prevented from commenting at the time at the request of the police.

In the wake of the brutal murder - Rachel was stabbed 49 times - Mr Stagg was identified as the chief suspect by police despite there not being a shred of evidence against him.

Scotland Yard detectives approached Mr Britton to help them find her killer and he was asked to produce an offender profile as they grew more desperate to solve the high profile murder.

Police became fixated with the profile matching the personality of Mr Stagg.

They devised Operation Edzell, in which an undercover officer posing as a lonely hearts “Lizzie James”, spent more than five months trying to ensnare Mr Stagg, encouraging him to confess to the murder.

In a taped conversation released by police, "Lizzie" said: "If only you had done the Wimbledon Common murder, if only you had killed her, it would be all right." Mr Stagg replied: "I'm terribly sorry, but I haven't."

Nevertheless, Mr Stagg was charged with Rachel’s murder in August 1993 and spent 13 months in custody before the case came to trial. On day one, Mr Justice Ognall excluded the entrapment evidence and threw the case out, refusing to put it before the jury and accusing Scotland Yard of “deceptive conduct of the grossest kind”.

Despite going free, Mr Stagg continued to be vilified until 2008, when Robert Napper, a serial killer and rapist, was convicted of Rachel Nickell’s manslaughter. He had previously been convicted of the 1993 double murder of Samantha Bisset and her daughter Jazmine.

In the new documentary this week, Mr Britton insisted that he had raised questions from the beginning about the legality and ethics of the police sting. He also told the programme he had never been paid by the Met for his work and said that although he had a “psychological role” in Operation Edzell, he had played no part in the “crafting” of the letters.

In the documentary, Gary Copson, a former detective chief inspector, who had been involved in the use of psychological profiling as a policing tool, backed him up. “They [the Met] took advantage of Paul Britton. In no way more than when everything went wrong,” said Mr Copson.

Mr Britton said: “At the beginning, I had been asked by the Met and others not to say anything. That caused some difficulty for me.”

He said he became the “focus of attention” when the sting operation was exposed.

Asked if he regretted not breaking his silence sooner, Mr Britton said: “I regret that this matter wasn’t put into the public domain years ago, and this in turn has affected the way I’ve been perceived, but I kept my word and stayed quiet. But some of the police officers involved have since spoken out and also the matter was starting to be fictionalised and dramatised and I didn’t want the truth to be obscured.”

Mr Stagg was awarded more than £700,000 compensation by the Home Office for the police blunders that led to his wrongful prosecution.

He told the Telegraph that he wished Mr Britton had spoken out earlier in his defence to help clear his name. He said: “I can't completely forgive that. But it's a start. I see him as more of a human being after our meeting and I did shake his hand.

"He should have spoken out to help vindicate me, any time in the past 28 years. I do believe his claim that a senior Met officer ordered him to say nothing. It suited them to paint me as the man who got away with murder on a technicality.”

The Murder That Changed Britain will be broadcast on CBS Reality on Tuesday, November 15.