By Robert Pigott BBC religious affairs correspondent

Dr Rowan Williams was attempting to prevent a worldwide split

When Anglican archbishops gathered in Dar es Salaam in Tanzania for another crisis meeting at the brink of a permanent split in the Communion, it was doubtful they would all stay in the same meeting room, let alone agree a joint statement.

Then past midnight on the final day they produced an astonishing compromise, somehow maintaining unity in the face of the deepest disputes on matters of fundamental belief.

"If you'd asked me a week ago for the odds that no-one would walk out, I have said they were remote," said the Bishop of Durham, Tom Wright.

"If you'd asked me what chance there was of a unanimous agreement, I'd have said it was nil."

Dr Wright was one of the authors of the Windsor Report, a sort of road map for the Communion to weather the apparently mortal crisis brought about by the ordination of a gay bishop - Gene Robinson - in 2003.

He credits the Archbishop of Canterbury, Rowan Williams, with preventing, or at least postponing, schism. "I don't know how he did it," he said.

Liberal approach

Dr Williams did it by persuading the Episcopal Church - or at least its presiding bishop Katharine Jefferts Schori - to make an outstanding sacrifice.

As the price of staying in the Communion, Dr Jefferts Schori had to agree the establishment of a parallel church organisation in America, as a home for traditionalists who have broken away from the Episcopal Church because of its liberal approach to homosexuality.

To make it worse, this alternative church body would come under the jurisdiction of a senior cleric, answerable, not to her, but to a committee of archbishops outside the United States.

It's an experiment - pray for it Rowan Williams Archbishop of Canterbury

It was enough to placate the conservative archbishops - especially from the Nigerian, Kenyan, Ugandan, Rwandan, Singaporean and South American branches of the Communion - who wanted to expel the Episcopal Church altogether.

Some of them have already intervened with traditionalist congregations in the United States, and will, for the time being, be allowed to continue to do so.

But the conservatives won even greater concessions.

An official Communion report saying that the Episcopal Church had just about done enough at its convention last June to conform to the Windsor Report's demands on homosexuality was sidelined.

Instead there was an uncompromising demand for an unequivocal promise not to ordain any more gay bishops or bless further same-sex relationships in church.

There will also be a covenant - a framework of shared beliefs and duties for membership of the Communion - with a sting in its tail.

Hard to sell?

It provides for measures to sever ties with churches that step out of line.

Dr Williams acknowledged that all of this - especially the parallel traditionalist church in America - was uncharted territory.

"It's an experiment," said Dr Williams. "Pray for it."

Could it work? There are signs that Dr Jefferts Schoi will find it hard to sell to her church, although Dr Wright believes "they will see that it's the only way of staying in the Communion".

That won't necessarily be enough to persuade them.

Divided Communion?

The Episcopal Church may be small (2.3m churchgoing members, compared with a claimed 18 million for the Nigerian church for example), but it is rich, and could be joined by like-minded churches in Canada, Mexico, Brazil, Australia (or most of it) and New Zealand, among others.

It is also hard to see the Episcopal Church being able to prevent its members - for whom social justice towards gay people is as much a defining issue as obedience to a literal interpretation of the Bible is to African conservatives - from blessing gay couples in church, or, one day, electing another Gene Robinson.

That is why Rowan Williams' coup has probably bought time rather than solved the crisis.

He has spoken of falling back on a two-tier Communion - with full membership of those who sign up to the covenant (the conservatives, the Church of England) and associate membership for those who do not (the Americans and Canadians perhaps).