Ministers preparing for next month’s G8 summit have announced plans to create a central database of internet paedophiles. Such a database would necessarily include the names of those convicted as part of Operation Ore, the huge police investigation launched three years ago on the basis of a list of 7,200 names supplied to British police forces by American colleagues.

The men on the list are accused of having paid for child porn through Landslide, a website that operated in Texas from 1996-9. So far, about 1,200 cases have resulted in convictions. The public has been led to believe that a huge number of unsavoury — and possibly dangerous — men have been brought to book.

There is no dispute that abusing children is a hideous crime. But it is also appalling to be accused unjustly of such a crime. My investigations and work as an expert witness in a number of Operation Ore cases have led me to believe that the evidence has been exaggerated and used unacceptably.

The costs — in every sense — have been huge. Thousands of cases have been investigated, with scores of officers spending hundreds of weeks sifting through computers and disks. Thousands more may face investigation. Meanwhile, the accusations have led to 33 suicides, most recently that of Royal Navy Commodore David White, the commander of British forces in Gibraltar. On January 8, he was found dead in his pool.

Ministers appear not to have been informed that critical evidence from US investigators forming the backbone of Operation Ore has been found to be untrue. In information given to Interpol and in sworn statements submitted to British courts in 2002, Dallas detective Steven Nelson and US postal inspector Michael Mead claimed that everyone who went to Landslide always saw only a front page screen button offering “Click Here (for) Child Porn”.

According to them, this was the way in to nearly 400 pay-per-view websites, almost all of which specialised in child pornography; ergo, anyone who accessed Landslide and paid it money must be a paedophile.

When Operation Ore was launched in Britain in May 2002, pictures of the web page and its “click here” button were given prominent and sustained publicity. But what passed almost unnoticed eight months later was that after British police and computer investigators had finally examined American files, they found that the “child porn” button was not on the front page of Landslide at all, but was an advertisement for another site appearing elsewhere: thus the crucial “child porn” button was a myth.

Landslide certainly gave access to thousands of adult sex sites. But accessing such material, which is now freely broadcast and sold in high street grocers’, is not a crime.

The real front page of Landslide was an innocuous image of a mountain, carrying no links to child porn. There was “no way” a visitor to Landslide could link from there to child porn sites, according to Sam Type, a British forensic computer consultant who was asked by the National Crime Squad (NCS) to rebuild the Landslide website. She dismissed the idea that Landslide had created a service devoted to child porn. She described it as different merely in that it was a “ pay-per-view” service.

Landslide operated two services, one of which gave access to thousands of sites for a small monthly fee. The other, called Keyz, was more expensive and required a separate payment for each site. The American investigators, it transpired, had copied the contents of 12 sites out of nearly 400 accessible through Keyz. Those sites definitely did contain child porn. It was also suspected that about a quarter of the other sites contained child porn. But investigations carried out more than a year after Operation Ore was launched found that about 180 Keyz sites were likely to have been adult sites only or were completely unknown. “We are unable to say what material these sites ever contained,” a police report stated.

This was not a problem in early cases, which relied on actual possession of indecent images. But the length of time since the alleged offences occurred — Landslide shut in 1999 — meant that in many cases, there were no indecent images, just the record of name and credit card details.

Here, the American evidence that having paid to get into Landslide meant having paid to access child porn has become crucial. Many of the accused argue that their card details could have been stolen and used without their knowledge, or admit that they used Landslide, but for adult material.

The NCS detective who found the real, innocuous Landslide front page in the American police files acted quickly to make it available to police forces and prosecutors. But nobody seems to have paid attention to the contradiction this created in the Operation Ore evidence. Nor did they apparently notice that there were now two, utterly different “Landslide front pages” presented in Operation Ore prosecutions — one totally incriminating, the other (and accurate) page quite innocuous.