By Robert Pigott
BBC religious affairs correspondent
Bishop Nazir-Ali is the most senior CofE figure to boycott Lambeth
For a century the Lambeth Conference has been one of the events keeping intact this largest Protestant church grouping in the world.
Now, for the first time, and just when the Anglican Communion is most at risk of disintegration, almost a third of the bishops invited to attend have decided to boycott the meeting.
It is a blow to the Archbishop of Canterbury Rowan Williams who wants to use the conference to heal the rift over sexuality which has driven the Communion to the brink of a permanent split.
The 250 bishops who have said they will stay away from the conference are attending what amounts to a rival meeting in Jerusalem.
They take a traditional view of biblical teaching on sexuality - that the Bible rules out active homosexuality.
The meeting - entitled Global Anglican Future Conference - is discussing what appears to be a blueprint for a separate communion.
The signs are that Gafcon will decide against an immediate split, but the boycott of Lambeth is an early sign of how much influence a powerful traditionalist lobby could have inside the Communion.
Most of the bishops staying away from Lambeth are from a few large churches, in countries such as Nigeria, Kenya and Uganda.
The decision by English bishops to join them is a big psychological boost.
"It's fantastic news", said Henry Orombi, Archbishop of Uganda.
"We are four thousand miles away from Lambeth, but they are right on the doorstep. This is a very powerful message that they can't ignore."
The latest to join the boycott is the Bishop of Lewes, Wallace Benn.
He said he had written to the Archbishop of Canterbury Rowan Williams to say he could not attend the meeting while liberal American bishops were on the guest-list.
Bishop Benn said the conference would present a false impression of harmony in the Communion.
He said he would feel hypocritical pretending to be on good terms with people he felt were distorting traditional Anglican beliefs about the Bible and homosexuality.
Bishop Benn also accused liberal American and Canadian bishops of persecuting clergy who wanted to stick to a traditionalist line.
"The reason I don't think I can go (to Lambeth) is that I can't pretend to have fellowship with people with whom I know there is broken fellowship, and sit down and take communion and have meals with as if nothing had happened, with people who are persecuting my friends in North America."
The Bishop of Rochester, Michael Nazir-Ali, is the most senior Church of England figure to say he will not attend. He said in a statement that "those who have gone against church teaching should not attend representative Anglican gatherings".
Dr Nazir-Ali agreed that the Lambeth Conference could therefore be only the first of many meetings to which traditionalists refused to go - if liberal Americans continued to be invited.
The traditionalists meeting in Jerusalem have grown frustrated at the "soft power" of the Archbishop of Canterbury alone to choose who is invited to the Lambeth Conference.
The Archbishop of Sydney, Peter Jensen, is one of those who have said the time has come to turn the Communion from being a British Empire into more of a Commonwealth, and accept that leadership will also come from elsewhere.
Archbishop Jensen - who has turned down his invitation to Lambeth - said it was significant that so many bishops had proved willing to do the same.
He said: "It tells us that the Lambeth Conference is not as important as it once was."