John Smyth, a distinguished barrister and friend of the Archbishop of Canterbury has been described as the Church of England's most prolific serial abuser in an official inquiry into his activities.

In 2017 Channel 4 News revealed that Smyth groomed boys and young men at Christian summer camps, universities and Winchester College, before subjecting them to savage beatings.

Following our investigation the Church of England commissioned a review led by former social services director Keith Makin. It sets out the horrifying scale of the abuse over many decades in the UK, in Zimbabwe and South Africa, accusing church officers of a cover-up.

And it's damning about the failings of senior church leaders -- including the Archbishop of Canterbury Justin Welby.

The review says that over a forty year period John Smyth became "arguably, the most prolific serial abuser to be associated with the Church of England," operating in 'three different countries and involving 'as many as 130 boys and young men."

A vicar compiled a secret report about Smyth's abuse in 1982. But the Makin review says senior members of the church participated in a 'cover up' of it.

Within a few years several bishops and "very senior figures within the Church of England, or [those who] went on to very senior positions including Archbishops and Queen's Chaplains" had got wind of what was going on.

At the heart of the Makin review is a damning indictment of failings at the very top including the Archbishop of Canterbury himself.

It says: "From July 2013, the Church of England knew, at the highest level, about the abuse that took place in the late 1970s and early 1980s. The Archbishop of Canterbury's personal Chaplain (a Priest) and the Bishop of Ely were all made aware of the abuse, and Justin Welby became aware of the abuse alleged against John Smyth in around August 2013...There was a distinct lack of curiosity shown by these senior figures and a tendency towards minimisation of the matter."

In response to our original investigation Justin Welby told us: "I genuinely had no idea that there was anything as horrific as this going on..If I'd known that I'd have been very active but I had no suspicions at all."

The Makin review says this was one of many "incorrect assertions" and that "enough was known to have raised concerns upon being informed in 2013."

Smyth's victims are calling for Justin Welby to resign.

Smyth left the UK in 1984 for Africa, where he continued his abuse.

The Makin review again criticises Justin Welby for failing in his 'personal and moral responsibility to ensure the church authorities in Cape Town knew of the dangers'.

No fewer than five police forces in the UK were told of Smyth's abuse between 2014 and 2016. After our original investigation, Hampshire police reopened their inquiries. But in the very month they tried to contact him for an interview, Smyth died suddenly in Cape Town in August 2018.

Victims are now demanding that the Church be stripped of its responsibility for handling abuse allegations.

That may now be a matter for Archbishop Welby's successor. Whoever takes over has a formidable -- perhaps an impossible -- challenge to ensure justice is done for abuse survivors.

We went to Winchester College, the former Bishop of Ely and the Archbishop of Canterbury's former Chaplain for comment.

WATCH THE INTERVIEW HERE: https://www.channel4.com/news/exclusive-report-reveals-church-of-england-cover-up-of-abuse-from-barrister-john-smyth

Archbishop Welby's statement: https://www.archbishopofcanterbury.org/news/news-and-statements/john-smyth-review-personal-statement-archbishop-canterbury