When the 13-year-old arrived at Yew Tree Farm near Stourbridge in the West Midlands at about 4.20pm on 19 September 1978, the elderly residents were out, but the door was ajar.
Carl stepped inside and was killed by a single shotgun blast to his head. His body was found 90 minutes later slumped upright on a settee with his bag still hanging over his shoulder. The nation was shocked at the terrible killing and a huge murder inquiry was launched by the West Midlands police force.
For the first eight weeks the police had few clues, but in November they believe they had a major breakthrough when four men robbed a farm about a 30-minute drive from Yew Tree Farm.
Two men with a sawn-off shotgun robbed an 83-year-old retired farmer and his three elderly sisters of pounds 300 at Chapel Farm. One of the women was pushed to the ground.
The getaway car was linked to Vincent Hickey, a 23-year-old small-time Birmingham criminal, who had already been interviewed about Carl's killing. He was arrested and began talking almost immediately, although later retracted his story.
In an apparent attempt to gain bail or immunity in exchange for information, he told them that his cousin, Michael Hickey, then 16, had taken part in the Chapel Farm robbery and also implicating James Robinson, 43, and Patrick Molloy, 49, who both had criminal careers, involving burglary.
Robinson had been in and out of jail for much of his life and in September 1978 had bought a shotgun which he had used in a robbery.
Both admitted the robbery at the second farm but strongly denied killing Carl Bridgewater.
Molloy, who for 10 days was denied access to a lawyer, at first denied the murder but later, according to police, made a statement saying he had gone to Yew Tree Farm with the three others. He said he was upstairs searching for antiques when he heard a shot. He dashed downstairs to discover the boy lying dead on the sofa.
Largely based on that "confession'' the four were charged with murder. There was little other evidence. There was no forensic evidence linking them to the farm, and neither the vehicles in which they allegedly travelled nor the stolen antiques were found.
Nevertheless, Molloy's confession dominated the trial. The men were convicted at Stafford Crown Court in 1979. Vincent Hickey and Robinson were sentenced to life with a recommendation that they each serve 25 years; Michael Hickey was ordered to be detained at Her Majesty's Pleasure because he was under 17 when the crime was committed; and Molloy was jailed for 12 years for manslaughter.
After the conviction, Molloy retracted his confession which, he alleged, had been beaten out of him by officers from the West Midlands Serious Crimes Squad. He died in Leicester Royal Infirmary in 1981 after collapsing in the prison exercise yard.
At the remaining three men's first appeal a few months later, Lord Lane, the then Lord Chief Justice, said a claim that the murder had been committed by Hubert Spencer, an ambulance controller and part-time antiques dealer, who lived nearby, was a "red herring". Spencer, who later served a sentence for another shotgun murder, has always denied involvement.
Since then, doubts about Molloy's confession, fuelled by a three-month rooftop protest by Michael Hickey in 1984, have led to a high-profile campaign to free the so-called Bridgewater Four.
The campaigners, who include the investigative reporter Paul Foot and Ann Whelan, Michael Hickey's mother, have helped make the Bridgewater case a miscarriage of justice to compare with the Guildford Four and Birmingham Six cases.
In 1987, Douglas Hurd, the then Home Secretary, referred the case back to the Court of Appeal. A witness who testified at the trial that Michael Hickey had admitted the murder confirmed that he had made up the story. But an eight-week appeal, the longest in British legal history, was dismissed in January 1989.
In 1991, a dossier was sent to the Home Office including evidence from a speech-pattern expert that Molloy's confession was fabricated.
Another Home Secretary, Kenneth Clarke, asked Merseyside Police to conduct a new investigation into the case - the sixth to have been held - but announced in February 1993 that "nothing had emerged" to cast doubt on the safety of the convictions. In May 1993, Timothy O'Malley, foreman of the trial jury, said publicly that he was convinced the four men were innocent. Since then a second juror has said that she believed the men were innocent.
The decision to refer the case to the Court of Appeal for a second time was largely due to two pieces of evidence. The new aspects were that the police discovered a set of unidentified fingerprints on the bicycle used by Carl Bridgewater. This was not disclosed at the original trial. The men's lawyers believe the prints could have been left by the intruders at the farm, who threw it into a pig-sty.
Earlier last year, a senior prosecutor in the office of the Director of Public Prosecutions, who had been involved in the original trial, urged the Home Secretary to reopen the case because of the fingerprint evidence. It also emerged that Molloy had not been formally arrested on suspicion of the Bridgewater murder when he made his alleged confession.
The officer who took the confession was the late Detective Constable John Perkins, who had been a member of the discredited West Midlands Police Serious Crime Squad and one of two officers later disciplined over a 1986 case involving allegations of fabricated statements - one of a series of cases which led to the disbandment of the squad in 1989. A number of other convictions involving evidence given by Perkins have also been quashed by the Court of Appeal.
Despite the new evidence, Mr Howard announced in December 1995 that he was not minded to refer the case to the Court of Appeal. But last July he changed his mind after further representation by lawyers.