The delegation has the support of the liberal Primate of the American Episcopal Church, Bishop Frank Griswold, who presided at the consecration of Gene Robinson as Bishop of New Hampshire.

Bishop Griswold is also understood to have brought forward a trip to London. The bishop, who faces the humiliating prospect of being barred from the annual primates meetings, the highest Anglican council, was due to fly to Britain on Friday but will now leave the US today.

"Spouses thereby ensure the survival of society and culture, and rightly deserve specific and categorical legal recognition by the state.

"Any attempts to change the meaning of the word 'spouse' contradict right reason: legal guarantees, analogous to those granted to marriage, cannot be applied to unions between persons of the same sex without creating a false understanding of the nature of marriage."

Mr Millar, who helped to pioneer the Alpha course that has revived evangelical Christianity in Britain and worldwide, will serve in Uganda and London, where he will be titled Bishop in Mission.

An announcement is expected from Lambeth Palace later this week.

The scheme is understood to have been worked out by Dr Williams and the Bishop of London, the Right Rev Richard Chartres.

In July Rowan Williams, the Archbishop of Canterbury, ordained 14 priests in his cathedral. Nine of them were women and only five were men.

Last year the Bishop of Salisbury ordained 18 women priests and only eight men. About half of those in training for the priesthood are now women. The dramatic change raises the prospect of the Church of England becoming similar to professions such as nursing and teaching, where females dominate.