PUBLISHED: 22:00 GMT, 8 February 2014 | UPDATED: 17:05 GMT, 9 February 2014
At my Catholic boarding school in the late 1950s there was a jolly priest who heard my confession in his room rather than in a vacant confessional box. After I had recited my laundry list of petty sins, he asked if I was ever tempted to 'commit a sexual sin by myself'.
He suggested that I take out my penis so that he could examine it to see whether I was prone to sudden erections. I left the room immediately. The next year, his proclivities discovered, he was removed by his bishop to another school.
As a child barely out of infancy, I had joined the long queues in our parish church every Saturday to confess my sins. The confessor sat behind a grille inside a dark box like an upturned coffin, smelling of stale perfume and nasty body odours.
A priest at John Cornwell's Catholic boarding school asked if he was ever tempted to 'commit sexual sin' (picture posed by models)
I did not realise that we child penitents were guinea-pigs in the greatest moral experiment ever perpetrated on children in the history of Catholicism.
When I started my investigation into Catholic confession I was shocked to discover that young children were not allowed to go to confession before the 20th Century - in previous eras children did not make their first confession until their teenage years.
It was the anxious and pessimistic Pius X, Pope from 1903-1914, who decreed in 1910 that children must make their first confession at the age of seven. Evidently he had taken to heart the Jesuit maxim: 'Give me a child at seven and it's mine for life'.
Pius also declared that all Catholics, including children, should confess weekly rather than once or twice a year, as was traditional.
Adult Catholics responded enthusiastically throughout the next five decades. Children had no option. That papal decision was to prove calamitous for generations of young Catholics. Childhood confession prompted complexes about sex and unwarranted guilt and, catastrophically, it created ideal opportunities for paedophile priests.
By lowering the age at which children made their first confession, Pius exposed children to priests in unsupervised situations of extraordinary privacy and intimacy. A significant minority of those confessors proved to be sexual abusers.
Pope Pius X decreed in 1910 that children must make their first confession at the age of seven
Statistics of offences have revealed that the age group most prone to attack was seven to 13 - the precise child cohort admitted to obligatory confession by this papal decree.
The assumption was that priests were to be trusted. But cut off from women and the outside world, ignorant of child psychology, convinced of unearned privileges and entitlements, many clerics were trapped in emotional immaturity.
The French author and former seminarian (theology student) Georges Bernanos wrote that seminary (theological college) 'made schoolboys of us, children to the very end of our lives'.
The intimate relationship between children and their confessors was at best a recipe for inappropriate encounters; at worst it became a potential paedophiles' paradise.
Childhood confession, and the ideas it put into young heads, was oppressive. Instructions for the sacrament began at the age of five or six.
We were taught that sins which broke the ten commandments or the Church's rules were 'mortal'. In other words these sins killed the soul and earned punishment in the eternal fires of Hell. Unless they were forgiven in the dark box.
What possible sins could a Catholic child commit to deserve Hell for all eternity? Many of these 'mortal' sins were to do with breaking the Church's rules - such as being late for Mass on Sunday, or missing Mass; or breaking the Holy Communion fast.
This fast, when I was child, meant that you could not eat a crumb or drink even a minuscule drop of water from midnight the night before going to holy communion. Many children would agonise over whether they had swallowed a trace of toothpaste, or swallowed a bitten finger nail.
The writer Anthony Burgess recalled that he had joyfully looked up and opened his mouth on the way to his first communion. He swallowed a drop of rain water, then realised that he had broken the fast. He went to communion all the same, and thereafter believed that he was damned.
Above all, there were those mortal sins of 'impurity' in thought, word and deed. The nuns taught us that 'touching ourselves', or having a 'dirty thought', was 'impure'.
I remember wondering whether I had committed a mortal sin because I caught a glimpse of a girl's knickers as she high-kicked an Irish jig in front of the class.
'Childhood confession prompted complexes about sex and unwarranted guilt and, catastrophically, it created ideal opportunities for paedophile priests'
The imposition of frequent confession as children approached puberty was even more oppressive.
Many of my hundreds of respondents spoke of prying confessors. Priests asked bewildered girls indecent questions about their sexual thoughts. Some 60 per cent of the men who wrote to me recalled their confessors' prurient obsession with the 'mortal sin' of masturbation.
The generalised oppression of children through guilt constituted a form of abuse in itself. But the most insidious consequence of childhood confession was the crime of priestly sexual abuse.
It has been calculated across many developed countries that the incidence amounted to four per cent of the priest population, although in some places the incidence spikes to ten per cent.
Some Catholic apologists claim that this merely reflects the average proportion of paedophiles in the population at large. Given the vocation of a priest, this is like saying that the incidence of obesity among marathon runners should be the same as that in the general population.
More crucially the apologists overlook the profound impact of sexual abuse in a religious context, like confession. A leading priest-psychotherapist, Richard Sipe, has characterised clerical abuse in the confessional as 'soul murder', arguing that such attacks undermine not only the physical and psychological integrity of the victim, but spiritual integrity as well - and for life.
An ordained psychotherapist who has treated many paedophile priests in Britain wrote to me: 'In all those cases of clerical abuse I dealt with, the sacrament of confession was used by the molester to discover vulnerability and groom candidates for abuse.'
Circa. 1903 - Portrait of Pope Pius X on the Day of His Coronation
By the late 1950s priests were becoming not only confessors but mentors and counsellors, on trips, retreats, country walks, parties, journeys alone or in groups by car.
The exploitation of confession to seduce the young was often devious in the extreme. A 'Mrs GC' wrote to me of the sexual abuse inflicted on her sister in a parish in South London.
Mrs GC was seven at the time, several years younger than her sister. The priest, Father Brown, was a former missionary and popular in the parish.
When Mrs GC started going to confession, Father Brown would use her as a go-between to set up assignations with the elder sister.
'He would ask me in the confessional box, “Where is your sister... tell her to come up to my room.” '
Mrs GC said: 'It all came to an abrupt end when he took my sister to the races and sexually abused her on the train coming back. She became a depressive. I'm convinced it was because of this experience that she eventually committed suicide.'
Accusations of abuse within the confessional have involved a wide constituency of clerics and a variety of types of offences against boys and girls, as revealed in the Database Of Publicly Accused Priests in the US.
The material comprises a detailed list now familiar in many countries - including kissing, digital penetration of girls, sodomy of boys, the practice of 'scouting for victims' and 'using the confessional to learn children's weaknesses', the practice of 'masturbating young penitents seated on the confessor's lap' and 'plying children with alcohol'.
The most detailed reports of routine abuse in the confessional, typical of thousands of instances around the world and in Britain, have come out of Ireland. For example, in the course of a trial in Cork in 2010 a complainant told police that in 1983 he was on retreat and went to confession in a private room where the priest asked him to take off his clothes. The priest touched his genitals and kissed his lips.
A report contained in a child welfare document published by the Diocese of Cloyne told of an incident involving a girl and a priest at a retreat house in Ennismore. 'She was instructed to lie on the bed for her confession to be heard. The priest then abused her.'
According to the Murphy Report on paedophile priests in Dublin, a parish priest used to 'run his hands all over girl penitents inside their clothing and then kiss them all on the lips at the end of confession which was conducted in a private room'.
Attacks in confession frequently took place within institutions where children were vulnerable and had no parents to report to.
'Exploitation of confession was often devious in the extreme'
In a case publicised through the 2012 documentary film Mea Maxima Culpa, Father Lawrence Murphy, a serial abuser at a school for the deaf in Milwaukee, Wisconsin, used the confessional, and his ability to sign, to groom and debauch boys in his care.
Credible accusations have been levelled against highly placed clerics in different parts of the world. Cardinal Hans Hermann Groer of Vienna was accused of abusing up to 12 boys in the confessional. Some priests took extraordinary risks. In 1988, an entire class of girls at a Catholic school in Monageer, Ireland, complained that they had been sexually molested by a Father Grennan when he heard their confessions in the sanctuary of the parish church. He told the girls in the pews to keep their eyes shut.
During each confession he grasped the penitent child's hands in his hands and pulled her towards his private parts. He was also accused of 'putting his hands under their skirts and fondling their legs to mid-thigh level'.
The late Father Marcial Maciel, the Mexican founder of the international order of Legionaries of Christ and regarded as a saint during his lifetime, ordered boys of 12 and younger to masturbate him.
Sometimes he would encourage the boys to confess to him after the act and give them absolution. Interviews with priests jailed for sexual abuse reveal that they exploited confession to square the circle of their offending and pastoral lives. A priest in Australia admitted in court that he had committed acts of sexual abuse against children 1,400 times with 32 different confessors.
Pope Pius X in 1904, Vatican City, Rome, Italy
From the mid-1970s, Catholics in their hundreds of millions ceased to confess their sins.
Catholic sociologists of religion, like the late Father Andrew Greeley, believe that the ban on contraception, confirmed by Pope Paul VI in 1968, was the reason.
Most sexually active Catholics simply refused to believe that contraception was a mortal sin. They carried on practising their faith, going to Mass and communion, but ceased to go to confession. Many more rejected the faith along with papal teaching on contraception, sex before marriage, homosexuality, and confession.
My investigation revealed that the majority of practising Catholics born before 1970 detested the oppression of confession, and gave up on it when they became adults. Many cite how the liberations of the 1960s had encouraged a repudiation of authoritarianism within Catholicism.
The astounding irony is that while most Catholic parents never go to confession themselves, they still allow their children to make their first confession before receiving their first holy communion, typically aged seven.
Moreover, the Church insists that no child can make the important step of first communion until after he or she has been to confession.
These days priests hear the child's confession in the pews, or in a private room with armchairs. The instructions preceding the ritual are much less harsh than they were in the past, but there are catechists who continue to inculcate the teaching on mortal sin and Hell.
Not so long ago, one of my grand-daughters, aged eight, came back from a first communion class asking: 'Grandpa, is it a mortal sin to be late for Mass?'
Many Catholic schools encourage children of primary school age to attend confession as part of the religion curriculum.
And there are moves on the part of Pope Francis, and many bishops, to bring the faithful back to frequent confession.
Hundreds of Catholics who have written in response to my investigation accept that confession, now known as 'reconciliation', can have a beneficial part to play in their adult religious lives.
Most, however, would prefer to acknowledge their sins and receive a blessing in token of forgiveness as part of a congregation rather than in a one-on-one relationship with a confessor.
Some value 'reconciliation' as spiritual counselling at important junctures of their lives, for example before marriage, or in sickness, or times of life crises. But many, including child psychologists, see the persistence of obligatory childhood confession as both preposterous and fraught with danger.
Not only does it trivialise this ancient religious ritual but it continues to expose children to virtual strangers in situations of inappropriate intimacy and secrecy.
Backed by the convictions of many hundreds of lay Catholics, I have sent an open letter to Pope Francis and top cardinals in Rome, seeking a ban on childhood confession.
Francis is a listening Pope who wants to know what Catholics really think. I am confident it will reach him. I hope that he will act.
The Dark Box, by John Cornwell, is published on February 20 by Profile, priced £16.99. To order your copy at the special price of £14.99 with free p&p, call the Mail Book Shop on 0844 472 4157 or go to mailbookshop.co.uk.