Sunday night in late January, a coal-black sky and brutal chill in Ayrshire, as the faithful gather.

Not in church but in the welcoming glow of a house in Darvel, where Father Patrick Lawson, who has been removed from his parish by the Bishop of Galloway, John Cunningham, will celebrate a private mass. Father Lawson is recovering from serious illness and inside the house, as candlelight flickers up from the altar and illuminates his face, there is concern among his supporters.

He has been up sick the night before and the stress is showing. "Father doesn't look well," one says. "I saw him pulling up his trousers," says another, referring to the weight he has lost. Father Lawson smiles wryly. "I hope nobody misinterprets that."

But that is the interesting thing about Patrick Lawson's case. There is no scandal or priestly sexual impropriety - at least not on his part. The abuser in this tale walks free.

Last week, just days after supporters rallied to the house mass, he heard his appeal to Rome against his bishop's decision had been rejected. He will now appeal to the Signatura, the highest court in Rome, and is also taking an industrial tribunal case for unfair dismissal.

Last night, a group of his supporters returned to the principal parish church at St Sophia's, Galston, for the first time since his removal in September last year, to protest when a letter informing parishioners of Rome's decision was read out.

Not that the bishop explained anything. He would remain silent, the letter insisted, until all ­proceedings were concluded, "to protect the integrity of this process and the reputation of Father Lawson". As if there is some dark secret about Lawson, yet to be declared. What could it be?

There have been many abuser priests secretly moved and protected in the Catholic Church. Which of them has been publicly evicted? Yet in the last six months, two Scottish priests - Pat Lawson and Matthew Despard - have been removed from parishes. The two cases are very different but have one thing in common: both priests have spoken out against the church hierarchy. Pat Lawson has fought for the entire 18 years of his priesthood to have church authorities deal appropriately with a serious case of sexual abuse. Despard has spoken out on a separate matter: the secret culture of homosexuality within the priesthood. So what is really going on in the Scottish Catholic church?

There have been many cups of coffee over a kitchen table in the months since I first followed the story of Father Patrick Lawson's eviction. "You're a journalist," he would say. "What do you think will happen in Rome?" He'll lose. "Really?" and each time he said it, his blue eyes betrayed a glimmer of crushing disappointment.

"Won't justice prevail?" That's the first thing you need to know about Patrick Lawson: he believes not just in God but in justice. He admits to waiting for the church equivalent of the Wizard of Oz to appear and rectify all the institution's injustices.But in the months since the resignation of Cardinal Keith O'Brien for abuse of power the church has refused to implement any transparent processes and procedures that suggest justice is valued. Instead, there have been hushed platitudes about "forgiveness". Forgiveness means nobody need say anything and the currency of the Catholic Church is silence. It is another control mechanism.

There have been many years of silence for Patrick Lawson. To understand his story, it is necessary to go right back to 1996. Then a seminarian, he was posted to St Quivox, Prestwick, under the supervision of parish priest Father Paul Moore. One night, he woke to find Moore fondling him under the bedclothes.

He rebuffed Moore, but the parish priest continued to make advances. He also noticed Moore's secrecy about a locked cupboard. "I found a box of keys, and tried each one until it opened. At the bottom, were videos. I don't know what was on them. On the shelves were photographs, some with names on. Provocative photographs: young boys in different poses, some with hats on, naked at the beach. I felt really sick."

Lawson also discovered Moore had abused altar boys and reported this to his bishop, Maurice Taylor.

Taylor and Moore already knew one another. They went on holiday together, visiting a Vatican diplomat from Galloway, Father Peter Magee. Lawson says he found letters between Magee and Moore in the locked cupboard. Magee would later become the head of the Scottish Tribunal, the person responsible for issuing legal advice to the Scottish bishops.

For 17 years, Lawson campaigned for appropriate action to be taken over Moore's abuse. He gave names and numbers of victims to Taylor asking him to help them. Nothing happened. He asked that Moore be laicised - ejected from the priesthood. Nothing happened. Instead, Taylor told parishioners that Moore was going on a well-earned sabbatical. In fact, he was sent abroad for psychological counselling.

ON his return, he was given a presentation and a retirement home - an irony that has not gone unnoticed in Galston. Lawson has had to move back in with his elderly mother and has no house and no income except a small monthly pension the church pays while proceedings in Rome continue. They even deduct his removal costs from the pension each month.

When Taylor retired, Lawson approached his successor, John Cunningham. He also appealed to Cardinal O'Brien, just before news broke of O'Brien's sexual advances to his own priests, and appealed to Archbishop Philip Tartaglia. All refused to help. He felt constantly like an outsider. "Rooms would often go silent when I walked in," he recalls.

Fast forward to 2012. By now, Lawson was looking after three parishes and six towns, but became ill with bladder cancer. He arranged his own cover, receiving no help or visits from the diocese. Doctors advised him to cut his workload and he arranged cover for the parish he did not live in, St Paul's in Hurlford. It was already a divided community with a history of tension predating Father Lawson's arrival. People there were unhappy that they did not have a resident priest. But things escalated when the Vicar General, Willie McFadden, went to St Paul's without telling Lawson, and advised parishioners to put complaints in writing. A parishioner issued pro formas. Twenty-three complaints were received, at least one from someone outwith the parish.

When news of this ­orchestrated campaign leaked, Lawson's ­supporters swung into action. Over 200 letters of support were written. Bishop Cunningham ignored them. Now suffering from stress as well as cancer, Lawson submitted evidence from doctors advising that he could continue with work but only on a reduced basis. The bishop then used the very letters that had been written in support of him as evidence that he was too ill to work.

Although the bishop refuses to say publicly what this case is about, the official grounds for removal on church documents are threefold. Firstly, Father Lawson's ill-health. Secondly, the "loss of his good name" because of the complaints. And thirdly, the "grave harm" this division has done to the ecclesiastical community. But what was it really about? "We knew it was really about his stance over Paul Moore," says parish secretary Manuela Simonini.

The decision from Rome, a seven-page document, just rubber-stamps everything submitted by the bishop, saying the 23 complaints are from "upright and serious-minded parishioners". The 200 supporters, presumably, are not upright and serious. "I am appalled by the decision," says George Gardner, who organised the house mass to show Father Pat the support for him in the parish, "but even more by the blatant steps taken by the diocese to discredit him."

Gardner provided music for St Sophia's for 30 years but no longer attends. "Rome's decision just ignores the evidence. It is time to retaliate." When news of complaints began to circulate, explains Gardner, rumours in the community spread about what they were about. Had he stolen from the church? Invented his cancer? "Some of the rumours were spurious and trivial," says Gardner. "Some of them just downright lies."

If Rome believed that simply upholding the bishop's authority was likely to dampen down scandal and enforce discipline, the calculation may misfire. The authoritarian way the church has dealt with challenge, while simultaneously preaching "forgiveness" for those who have seriously abused their power, has created a standoff.

On one side is a growing number of priests and lay people who want change; on the other is an old-guard hierarchy, afloat in a turbulent sea of scandals, clinging to the old certainties of secrecy, obedience and control like lifebuoys.

Father Gerry Magee, another Galloway diocese priest, contacted Lawson immediately when he heard of Rome's decision. The bishop had assured priests Lawson had been informed, but he knew nothing.

Despite the letters being dated January 7, he did not receive his until January 30 - the day after his fellow priests were told. A mix-up in Rome, the bishop claimed. A disgrace, says Magee. Magee felt sick when he heard the decision, and contacted Bishop Cunningham immediately.

"What I ask, in God's name is going on here?" he wrote. "All that I am certain of is that all those responsible for this disgrace will be held accountable by God."

Another coffee over the kitchen table, but this time it is clear the stress is having a deep effect on Patrick Lawson. He can't sleep: "The vitriol I have experienced just goes round and round in my head." Some of the symptoms of his illness have returned, he confides. Perhaps, he says hopefully, it is just an infection.

He can't give up his fight for justice. He needs to raise €1000 Euro for his Signatura appeal: parishioners say they will raise cash. He has been granted legal aid for the employment tribunal case which will begin this month. It will centre on whether a priest is an employee or not. It is likely to be protracted but if he wins the right to have it heard at a tribunal, it will establish employment rights for all priests across Britain.

Excellent news, says American Canon lawyer Tom Doyle, who represents abuse victims worldwide. It is civil law, not Canon law, that will force the church to do the right thing. "Canon law is a legal system created for a monarchy," he explains.

Father Lawson's exposure of Paul Moore is not even mentioned in the ruling. "That is clearly the elephant in the sacristy and the main issue in the case. But the aggrieved person, Father Lawson, is involved in a process that is effectively controlled by the bishop and heavily weighted in the bishop's favour."

At 55, Lawson is one of the younger priests in his diocese. Despite desperate shortages, they want him out. "It makes me feel less …" He stops. Less what? "Less worthy." This is not about winning and losing, but about self-respect. You cannot lose when you do the thing that you know in your heart is right.

He is, though, focusing on civil rather than church justice. "The wizard," he says quietly, "is not going to show up. Is he?"