Yorkshire Ripper: The police mistakes that allowed Peter Sutcliffe to kill three more women

Thirty thousand statements, a quarter of a million names, millions of car number plates, but not one computer. They’d barely been invented.

All the information detectives gathered was recorded and stored manually on handwritten index cards - was it any wonder the Ripper squad was overwhelmed by paperwork?

The floor of the incident room in Leeds city centre's Millgarth police station had to be reinforced to cope with the weight of the files in their cardboard boxes. Imagine if there had been a flood or a fire.

Over five years, as more women were mutilated and killed, the clues that pointed to Peter Sutcliffe grew within that vast pile of evidence.

He was interviewed by police nine times, his car was spotted 60 times in red light districts where the Ripper prowled for victims. It was all there in that clogged up system.

West Yorkshire Police were clearly not prepared for the scale of the investigation as the elusive serial killer wielded hammers, knives and screwdrivers across the north of England

But don't take my word for it, read the damning words of the late Sir Lawrence Byford in his 1982 report into the police handling of the investigation, in which he wrote: "The ineffectiveness of the major incident room was a serious handicap to the Ripper investigation.

"While it should have been the effective nerve centre of the whole police operation, the backlog of unprocessed information resulted in the failure to connect vital pieces of related information.

He continued: "This serious fault in the central index system allowed Peter Sutcliffe to continually slip through the net."

But it wasn't just the avalanche of paperwork that engulfed detectives and delayed them for so long in identifying the murderer.

They were also blindsided by a troublemaker known as "Wearside Jack'", who pretended to be the killer on the loose and led them - for more than a year - on a wild goose chase that gave Sutcliffe time to kill three more women before he was caught.

John Humble, for reasons best known to himself, sent hoax letters and an audio tape that convinced police they should be looking for a man with a Sunderland accent, despite contradictory evidence from some Ripper survivors.

Sutcliffe should have been rising to the top of the suspect list, but instead he was slipping down it because of his West Yorkshire accent, and carried on killing.

It took an FBI criminal profiler and the squad's own dialect analysts to finally persuade senior detectives that "Jack'" was a blatant hoaxer. Humble was unmasked years later and jailed.

The Ripper case was also damned by allegations of misogyny with police convinced Sutcliffe was attacking only prostitutes. Victims who were not sex workers were initially disregarded.

That thought was carried into Sutcliffe's trial by prosecutor Sir Michael Havers, the attorney general, who said of the victims: "Some were prostitutes, but perhaps the saddest part of the case is that some were not.

"The last six attacks were on totally respectable women."

Sir Lawrence Byford's hard-hitting report led to big changes in policing, notably the development of a computer system that much better collated information and eased cross-referencing.

It also gave all police stations access to various databases.