Police believe that the violent but emotionally cold Morss, in particular, was likely to strike again. His lover, Tyler, told detectives that Morss was dissatisfied with the brief time they had spent having sex with Daniel. "Tim said it was a waste and he wanted another one."
Detective Sergeant Stephen Kavanagh said after the case: "We got them before that nightmare scenario occurred."
When Daniel first disappeared on 2 October 1994, police at first suspected that it might be the work of an organised paedophile ring, of the type involved in the killing of the rent boy Jason Swift, 14, and Barry Lewis, 6, crimes solved by the police through Operation Orchid in the late Eighties.
For a time Daniel's own mother, Maxine, and her then boyfriend were questioned over his disappearance, but they were later released. The Director of Public Prosecutions later ruled against continuing with separate child abuse charges against the couple.
The breakthrough in the case, codenamed Operation Gainford, came only after David's remains were found near a golf course at Bradley Stoke, Bristol, in March last year. This led to a BBC Crimewatch programme the following May which highlighted the continuing hunt for the boy's killers. Two men who had met Morss inside prison watched the programme, or heard about the details of the case from it.
Both - a psychiatrist and expert on child sexual abuse identified only as Dr B, and Edward Cook, a prison officer - were struck by the similarities with the detailed sexual fantasies of which Morss had boasted: the abduction, abuse, murder and burial of a young, blond, blue-eyed boy. Morss had been "most specific" about the boy's appearance, Dr B said. Daniel fitted these characteristics.
Within hours police were told of the link with Morss and he and his boyfriend, David Guttridge, were quickly arrested. Guttridge had no involvement in the murder but pleaded guilty to perverting the course of justice by helping Morss fly to the Philippines the month before the arrests.
Guttridge, Morss and Tyler all met in Wormwood Scrubs. Morss and Tyler came from similar backgrounds: Morss went into care as a child when his mother, Iris, could not cope; Tyler was put in a home after his mother abandoned him. Both were abused while in care, and in turn abused children as they became adults, Tyler receiving four years' youth custody for a string of offences and Morss seven years for acts of gross indecency.
Guttridge, 59, also had a criminal history of paedophilia but was determined to reform, and while all were in Wormwood Scrubs he introduced the two younger men to Dr B to help them. But neither pursued treatment with any enthusiasm and the sessions petered out.
Guttridge later said that the "whole point" of his relationship with Morss, whom he loved, was to rid him of his predilection for boys. They set up home together and Guttridge helped his friend start a florist shop in Bristol.
But Morss, a former soldier, kept in touch with Tyler, and his desire for young boys was reawakened. While Morss was a cold, remorseless killer with a powerful personality, Tyler was educationally sub-normal, a weak- willed, girlish-looking boy from a Barnardo's home.
It was Tyler who introduced Morss to the Philippines, where they buggered young local boys. Tyler featured in a dozen videos of himself with the boys, and in one he is seen haggling over the price of sex and reducing it from the equivalent of 75p to 50p.
Back in London in 1994, Tyler and Morss, then a minicab driver, took to cruising the streets together, excluding Guttridge, who owned the cab firm, from their trips.
The older man was jealous of Tyler and worried by his impact on Morss. He said: "I felt [the relationship] was based on their mutual requirement for young boys. It was just a means of winding each other up sexually."
On 2 October 1994, Morss and Tyler cruised the streets of east London in the minicab before selecting Daniel as their victim in Beckton.
Even after Morss confessed to him, Guttridge at first refused to believe that he was guilty. Only later did he accept that Morss, whom he conceded had a "warped and twisted" view of life, had killed Daniel.
Morss chose his "hunting ground" in part because he was not known there. But also because of its social make-up; parts are 86 per cent white working- class, with a high proportion of dysfunctional families and a large number of children - many blond and blue-eyed like Daniel - playing late on the streets. As a mini-cab driver he would have been aware of these factors.
The charity Kidscape, which aims to improve children's safety through direct education, is adamant that, while serious, the abduction and murder of children by strangers is rare in Britain. Over the last recorded decade, 1983 to 1993, the number of such killings averaged just over five a year. "The danger is out there," Jane Kilpatrick, assistant director of Kidscape, said. "But the number of murders by strangers has decreased since the [Second World War]."