IT was a Friday evening in late February 2013.

In an off-the-cuff conversation with the BBC and with an eye on his fast approaching retirement Cardinal Keith O'Brien voiced his view priests should be permitted to marry.

Seen as perhaps some politics as he and his colleagues prepared to appoint a successor to Pope Benedict, it none-the-less came as surprise from a man best known of late for his robust views on gay marriage and made global headlines.

By Sunday morning he was world news again. The reactions were not so complimentary. Three priests and another man who had left the clergy had complained to the Vatican that their one-time or current boss had been involved in "inappropriate contact" and "unwanted behaviour" with them.

The Catholic Church in Scotland was thrown into an unprecedented crisis, the Cardinal stepping down from his role as Archbishop of St Andrews and Edinburgh within a day. It was a "time of confusion and distress for Scotland's Catholics". The "issues" were "contested" not denied.

Leading historian Professor Sir Tom Devine described the saga as "probably the gravest single public crisis to hit the Catholic Church in Scotland since the Reformation".

But even his subsequent admission that his sexual conduct had "fallen below the standards expected of me as a priest, archbishop and cardinal" failed to contain the scandal.

In fact it was about to unravel further. A former trainee priest approached The Herald with new allegations of sexual misconduct, claiming he was abused by the disgraced cleric as a teenager.

The former seminarian, who had known the cardinal since childhood, broke a 30-year silence to tell how he had been groped and kissed by Cardinal O'Brien in the 1980s, a clear indication the previous allegations were not isolated episodes.

It then emerged he was also being investigated for sexual misconduct in the Vatican on the very night he was made a cardinal.

The Herald revealed the Cardinal was alleged to have assaulted a priest at the Scots College in Rome in October 2003, hours after being awarded the red mitre by Pope John Paul II, with a London-based priest making a formal complaint to the Vatican the previous September.

There then followed claims one member of the priesthood had been in a long-standing physical relationship with Cardinal O'Brien, with further claims the complaints against the cleric were spurred by gay priests angry at his rhetoric and hypocrisy about same-sex marriages.

In the six months building up to him being forced to stand down last month, the Cardinal had been under some pressure from priests to tone down the rhetoric.

His statements, such as describing homosexuality as a "moral degradation", were a tipping point for those previously close to him.

It has also emerged two of the complainants were very close friends of a priest in the Archdiocese of St Andrews and Edinburgh who committed suicide a decade ago, having attended Blairs College and Drygrange seminary with him.

He was found hanged in his presbytery by Cardinal O'Brien, a week before he was due to go on holiday with one of the complainers.

For Rome though it seemed the crunch moment came when he was photographed and spoke with a tabloid newspaper at his sometime residence in East Lothian.

Within hours the Catholic leadership had appealed to the Vatican to take action and initiate moves to keep him away from public life. The pleas were heeded.

Again, The Herald revealed the instruction came for the Cardinal to quit Scotland and shelve his plans to retire to a church-owned cottage in Dunbar.

Two weeks later, in a short statement, its first in the three months since the revelations broke, the Vatican said the cardinal would "be leaving Scotland for several months for the purpose of spiritual renewal, prayer and penance".

Until yesterday it was also the last statement Rome had issued.