But five years after the initial charges had been made the parents were granted leave to petition for nobile officium, the ultimate appeal in Scots law. Evidence which had been accepted for five years was suddenly thrown into question. A new sheriff said the child who’d started the whole process off was a devious, manipulative little boy and should be sent back home – despite admitting that “it is possible that this has been a case of child abuse”.

By then the tide had turned. After a number of years of sensational convictions, there was suddenly a consensus among the media and the judiciary that there was no such thing as satanism. There were lying children, of course. Everyone knows the little sods lie all the time. There were also hysterical social workers, who, despite years of professional training, had all been swept up in a craze for madcap American thinking. And there were only innocent parents, poor victims whose children had been snatched from them and who must have their little darlings restored to them immediately. The family as the primary social unit was not to be questioned again – Britain’s newspapers would make sure of that.

The children in Ayrshire were sent home and so were the children who’d been removed from their homes in Orkney. They’d been taken to the mainland and housed with foster families in Highland region and in Strathclyde. There, they said the most bizarre things. One nine-year-old boy directed a play in which the “minister” was shown wearing split trousers revealing his bare backside, which the boy then hit. A seven-year-old girl in a different foster family became uncharacteristically aggressive when she was told she was going home and smashed a doll on the ground. She said she didn’t want to go and stood “like a wooden doll”, refusing to get dressed.

Such strange behaviour proves nothing, of course, though the fact there was so much of it in children from different accused families might surely have given the authorities pause for thought. Instead, Sheriff David Kelbie sent the children home without testing the evidence in court. This decision was criticised by the Law Society of Scotland and by Lord Clyde in his inquiry into the case, but that fact has been ignored for 25 years, to the extent that even as respected a news outlet as the BBC can report that the parents in Orkney were innocent. Innocent till proven guilty? Yes, but innocent beyond the shadow of a doubt? That, the Orkney parents can never claim.

Over the past 25 years I have written a number of articles on SRA and on recovered memory; I have gone back to Orkney to re-investigate; I have chased up members of the W family, the huge family at the heart of the case. Most of the articles have never seen the light of day. The one major piece I managed to get into the mainstream was in The Guardian Weekend magazine under the editorship of Deborah Orr. The house lawyer told her the article had a tendency to suggest the accused parents in Ayrshire were guilty. She chose to publish it in full.

Others were not so brave and it became one of the great frustrations of my writing career that I’d pour months of research into a piece, only to have it buried. One editor, on receiving an interview about a woman tied up in a cage for months, said she just didn’t believe such things happened. I’ve always wondered how she felt when Natascha Kampusch emerged from her years of captivity or when Elizabeth Fritzl talked about being imprisoned and raped by her own father.

EVEN those who deny the existence of international satanist networks can hardly pretend that satanist abuse never happens – in 2002 Manuela and Daniel Ruda were convicted by a German court of killing Frank Haagen, carving a pentagram into his stomach and drinking his blood. In 2011 Colin Batley was convicted of leading a satanist cult in the west Wales town of Kidwelly. Among other things he committed 11 separate rapes, three indecent assaults, six counts of buggery and four counts of possessing indecent images of a child.

Over and over again satanist abuse has been proved to exist, so why does so much energy go into denying it? I have never been able to understand it and in the end decided to have one final shot at putting SRA into the public domain again. I’d been talking to Bob, a survivor who’d been abused by a satanic sex ring as a child. Although he’d made a life for himself with marriage and a good job, his memories had started to take over his life, he’d lost the job and was now struggling to survive. I told him I probably wouldn’t be able to get his story into the papers, but he said it would help to talk about it. It was he who suggested I fictionalise it.

I was dubious at first because this form of abuse is so sensational in its essence that it’s hard to believe. People who’d tackled it before either went for horror, like Dennis Wheatley, or else drew in elements of the supernatural, as in Phil Rickman’s Midwinter Of The Spirit, recently dramatised on television. I find it hard to believe in the spirit world so the latter was not an option.

What I settled for was to make the story as real as possible and in doing so, to demystify it. Whether the perpetrators believe in the dark gods is irrelevant to me but what they do to their victims has haunted me for years. They tell children that satan always sees them – he’s the spider in the corner of the room or the staring-eyed cat. They have no freedom in their heads, which seems to me the cruellest abuse of all.

It was natural to set my novel, Dark Web, in Orkney, not just because I knew about the historic case but because the landscape there is so imbued with human history. The Neolithic village of Skara Brae, the chambered tombs all over the islands, the immense standing stones of the Ring of Brodgar all form a dramatic backdrop that makes you question what it is to be human.

Although the book is short, it has taken a huge amount of time – writing, shaping, rewriting. Trying to make it credible in literary terms is not the same as telling the truth. The publisher who had an option on the book thought it was very powerful though had some questions about the Orkney setting. Still, when she invited me for dinner at her house I thought we were going to discuss publication dates – she wanted autumn but I wanted to go earlier, at the summer solstice, as the climax of the book is set on that day.

Over wine and salmon she told me the book was on an important subject and was powerful, indeed scorching. But she said her editor had said he’d resign if she published it. Choosing to locate the story on Orkney would cause people to be triggered, even if they’d only peripherally been involved. Some of them might even commit suicide. You wouldn’t set a novel about a spree killer in Dunblane, would you?

I don’t think anything is barred to a writer, but she said I was immoral and heartless for even considering it. Given that the book has been driven all along by a concern for the survivors of SRA I found that hard to take, but also deeply puzzling. People who commit suicide generally do so because they find themselves unable to carry on with life, not because they’ve read something on a subject they already know about. People don’t normally threaten to resign over a book. My first two fictional books were nominated for literary prizes and one had been promoted in WH Smith, so such obdurate resistance was unexpected. As our argument became more robust her whole response seemed to me to be more and more irrational.

After years of struggle I shouldn’t have been surprised but I am still baffled. The setting won’t please the people of Orkney, who I’m sure would like to forget that the scandal of 25 years ago ever happened. But then I’m not writing for their tourist board – and the irony is that the book’s early readers have all really liked the evocations of the Orkney landscape. It seems to me that if the novel upsets anyone involved in the case it’s likely to be the people accused of abuse. My concern is not for them, because I believe they’re guilty – but that’s only my opinion and because it hasn’t been tested in the courts I can’t prove it.

Just as they can’t prove they’re innocent.

We’re supposed to be free to express our opinions in this country, but you wouldn’t think so from the way the publishing industry has reacted so far. I’ve approached over 30 agents and publishers and they have all said no.

Well, I say no too. No to pretending that families always provide ideal homes. No to abusing victims twice, the second time by refusing to believe them. I say no to depriving children of support, to making professionals unable to protect children properly. No to covering up the darker aspects of human nature till we’re absolutely forced to acknowledge them. Do we always have to wait till people are dead before we’re brave enough to expose them? To my knowledge, former prime minister Edward Heath was reported by at least five people to have been involved in satanic ceremonies. But the people who reported him were patients, so who could believe them? Right?

If I sound angry it’s because I am. Allegations of varying kinds of sexual abuse against Heath have now been received in eight different police authorities. The current inquiry, involving 4500 boxes of Heath’s personal papers, is being overseen by Wiltshire Police, who were investigated by the Independent Police Complaints Commission in 2015 for allegedly failing to follow up similar accusations in the 1990s. Well, maybe they’ll get it right this time, when there’s no powerful political figure to go up against, when officers won’t slide down the promotions ladder because they’ve offended the wrong person. Maybe the press, society’s guard dog, will get it right now there’s no danger of being sued for libel. There is, after all, no risk in accusing a dead person.

The convictions, the ritual shamings of perpetrators, the public apologies are always, always, too late.

DAVE MARROW FROM ORKNEY