A GREENOCK priest has spoken about his role as the official exorcist of the Roman Catholic Church in Scotland.

Father John Bollan has not yet had to perform a 'full' exorcism - the mysterious ritual mythologised by infamous horror movie The Exorcist, which the church believes can expel demons in possession of a human being.

But according to the Vatican, demand worldwide is on the rise and it has just started training 50 new priests as exorcists as a result.

Exorcism exists on a spectrum of what Father Bollan calls 'interventions', with different stages of possession where demons beset a human being rather than possess them.

The church also deals with 'infestations', instances where a home or an object is, for want of a better word, haunted.

Father Bollan said: “The most dramatic incidence of a problem I dealt with in a house concerned people who are not the least bit suggestible, they were doctors, in fact.

“This family, over a period of time was worn down and became ill as a result of what was going on.

“Very often in this kind of ministry you arrive just after something’s happened, or you happen to leave just before it happens but in this particular case there were things happening while I was there – noises coming from within stone walls, the family pets becoming highly agitated.

"I remember, because it was the middle of a scorching summer, being enveloped in a pocket of icy air.

"There were footsteps in the house on one occasion when I was the only person there.

“Some of the other things in connection with that specific case were genuinely frightening, because everything that you are used to tells you this shouldn’t happen - it’s subverting the laws of physics, it’s subverting your understanding of how you think and how you know the universe works. That’s what gets you. It’s because it turns upside down your understanding of how nature works and how gravity works. It’s a curiosity, and it’s an unsettling experience.”

While fictional depictions of the dark spiritual world often focus on demonic possession, Catholicism believes it is most often preceded by demonic oppression.

Fr Bollan said: “Oppression is where you’re being picked upon, it’s like being bullied by something or someone you can’t see. It’s about being undermined in terms of how you see yourself, how you see your life, how you see your relationships and so on. It’s not simply in that psychological sense of having depression or having a negative mindset, I don’t want to blur those, it’s a spiritual undermining of all that’s good in your life.

“Possession is where the person’s freedom, the person’s identity, becomes constrained. There are obviously some parallels with personality disorders, but this is something else coming in and taking control of their lives and taking control of their relationships and in a much more dramatic way.”

According to the church, signs of possession which set it apart from mental health disorders include supernatural knowledge.

Father Bollan says he remembers a priest who once taught him in Rome who would often shed his priestly clothes when meeting possible sufferers, or hide holy communion in his pocket, and if a dark force was indeed present the demonic being would have instant knowledge of the eucharist in his pocket, and react aggressively.

Fr Bollan says when he is approached by anyone with concerns about demonic oppression or possession, a thorough medical investigation is his first priority. Only when medical and psychological explanations have been ruled out will the church intervene, he says, and if a case does lead to an exorcism, the church requires the presence of both a doctor and a psychologist.

The St Joseph's priest – who has a degree in psychology, a masters in spirituality and a history PhD - believes his main strengths lie on the investigative side, or 'spade work', as he calls it.

He said: “Sometimes people are living in abject poverty and they’re living in a standard of housing that is really not fit for habitation.

“Sometimes one gets the sense that it is a way to try and co-opt the church into applying pressure onto a councillor or housing association to get out of there – admittedly it’s a fairly desperate attempt, but that can be part of it, so it is important to go and spend time with people when they say they’re experiencing something.

“While people might be sceptical of the whole process, what they might not realise is that there’s a very careful analysis that goes on, and it involves medical personnel and psychologists.”

Once social problems and medical explanations have been ruled out, if Father Bollan believes he has a real case on his hands he sends a report to the Bishop and recommends a course of action.

Over 15 years, he's dealt with just 15 credible cases, and while he’s never had to perform a full exorcism, he has witnessed apparent possessions.

He said: “I’ve been involved in praying with and praying over people who are being disturbed, and their reaction to being prayed over was similar in some respects to what people report in full blown exorcisms."