By Russell Findlay

When Bill Johnstone discovered he had an extensive criminal record, his initial shock and confusion quickly turned to anger.

Any police officer who checked the force computer system was told he was a serial convict whose 20-year history of offending included police assault and forgery, resulting in eight separate prison sentences.

In the eyes of the law, he was violent, dangerous and dishonest. Yet every word was a lie. Somehow, the supposedly secure database had been compromised.

Johnstone is not a criminal but a decent, hard-working family man and businessman. When the police said he was in prison, he had actually been putting his life on the line as a Royal Artillery officer, often serving in Northern Ireland at the height of the Troubles.

Speaking to STV News, Johnstone tells of his disgust and disbelief at being wrongly branded a criminal - and how he has lost almost ten years of his life fighting for answers and justice.

His story is the subject of a new book titled Fitted Up: A True Story of Police Betrayal, Conspiracy and Cover Up, written by myself, an STV News journalist.

The book's starting point is an icy night in November 2009 when Johnstone's bustling car repair and classic car sales garage in Hyndland, Glasgow, was destroyed by a fire.

CID officers allegedly failed to properly investigate claims that a disgruntled customer had threatened to torch the building, prompting Johnstone to formally complain about police inaction.

He said: "It was obviously terrible to stand there and watch that old building burning down with the classic cars inside and it wasn't until days later that we realised that nothing was being done.

"That was just the beginning of the nightmare that was to follow and obviously nobody could foresee what was going to happen after that, which is now a decade."

Over the following years, Johnstone, his partner Jackie Mills and their families became the targets of a sinister criminal vendetta.

Cars were torched and destroyed with chemicals and blades; they were stalked; a razor blade arrived in the post; deaths threats came in text messages and, on one occasion, threats were made against Johnstone's teenage daughters.

The couple reported each incident to police and placed their faith in the criminal justice system. Just like the many vehicles, that faith has now been destroyed. No-one was prosecuted for any of the dozens of crimes with police later admitting numerous failures.

He said: "The threats over the years went on and on, mainly text messages threatening more fire attacks but it just completely consumes your life because you can't work, you can't do anything, you couldn't park a car outside the house without it being set on fire or destroyed.

"We didn't know at that time that the police were doing nothing to help us."

Missed opportunities and botched or half-hearted investigations, however, were far from the worst of it.

In 2011 - by sheer chance - came the first clue that something was seriously amiss when motorcycle police officers handcuffed Johnstone at the side of the road and wrongly told him there was a warrant for his arrest.

Months later, the Crown Office sent him a copy of what the police said was his criminal record. Johnstone believes the toxic list of convictions was the main reason why the police failed to properly investigate the vendetta - a claim they deny.

He said: "The behaviour of some of these police officers was absolutely dreadful and to us at the time it was inexplicable. You just wouldn't know.

"You could not figure out what was wrong. What was wrong was they were judging me as that serious criminal.

"We're not talking about just a criminal record with silly things on it.

"This involved serious criminality including police assault and convictions for dishonesty, including forgery and that type of level of criminality.

"What they were doing was basically looking more at me to see if I was up to something rather than actually investigate."

But how did it happen? How could a law-abiding, ordinary person come to be assigned a criminal record? And if it can happen to Johnstone, how secure and accurate is information the police may hold about anyone else?

Johnstone has spent the past eight years trying to get answers. Instead, he says he has been told lies, been obstructed and had his life consumed by a Kafkaesque police complaints system which is not fit for purpose.

He said: "I don't feel helpless; I feel there's such a public interest here that outweighs any personal judgement on the police. I know what they've done. It's not just my personal view that the system is unfit for purpose.

"It's like a revolving door, you just go round in a circle. A good lawyer would struggle to get his heads round the process and they [police] control it from start to finish. It's fatally flawed because of that."

One two occasions, Johnstone was arrested and put on trial for crimes he did not commit. Neither case stuck but he believes both prosecutions were motivated by a desire to discredit him and shut him up - to silence his awkward questions about the record.

The police say the record was applied in error and lay the blame at an unnamed civilian employee. The truth - Johnstone believes - is that a rogue police officer maliciously added his details to the police intelligence database, as an alias of the real record holder.

He said: "As far as the record's concerned they came away with a story that was laughable, about how an operator had done it in error and she had left the job now so they couldn't speak to her to find out why.

"It took another three years after that to chisel an answer off them to do with the alias. But the only way that your details will be added to somebody else's criminal record, your full nominal details, is if there's an intelligence marker there that links you to that record.

"So they've never explained that. They have been asked continuously by my solicitor, by me, in writing. They simply ignore the alias question.

"They've told the Press in the past, they've told an MSP in the past that I had been given a full, comprehensive explanation. They've lied.

"They have to be made to properly explain how my full nominal details were taken and added as an alias to another subject's horrendous criminal record which linked me to that record so every police officer that I spoke to thought I was him.

"But even if it was a mistake, what a horrendous mistake that can destroy people's lives that they're trying to cover up. If it was a mistake they need to explain in public how that can happen to a person.

"It happened to me right after I complained about a CID officer."

Next month marks the tenth anniversary of the garage fire. The financial cost to Johnstone has been devastating - but as he nears retirement he does not know whether he can afford legal action.

He said: "There's no redress with Police Scotland. The only redress is if you go to a civil court and you've got a war chest of money to take them on.

"We need to think long and hard about whether we can do that."

STV News asked Police Scotland three questions about Johnstone's ordeal - but they failed to answer any of them.

The first was: Can Police Scotland provide us with an explanation about how Bill Johnstone was wrongly assigned a criminal record?

The second was: In light of what happened to Mr Johnstone, what reassurances can Police Scotland give about the integrity of its computer systems and the accuracy of information it holds about members of the public?

The third was: Mr Johnstone reported dozens of crimes spanning several years but no-one was prosecuted - why was there no prosecution and is there any intention to now do so?

Instead of answering our questions, they reissued a previous statement which repeated the claim that they had provided Johnstone with "a full and comprehensive explanation ... in relation to an error on our criminal record system".

They added: "The error took place on January 12, 2011 and was rectified on May 12, 2011.

"We strongly refute any suggestion that Mr Johnstone was adversely treated as a result of this."