The Archbishop of South Sudan, the Most Rev Justin Badi, has issued a clarion call to the orthodox bishops who will be attending the Lambeth Conference this summer.

In a video published on the website of the Global South Fellowship of Anglican Churches (GSFA) he urges them, "To speak with one voice, united in gospel truth," and states that they will be seeking for the Conference to reaffirm Lambeth I.10 as the official teaching of the Anglican Communion.

Lambeth I.10 is the historic resolution about marriage and human sexuality which Anglicans have been fighting about for the past 25 years.

It was drawn up and passed by an overwhelming majority of bishops at the Lambeth Conference in 1998, and it "rejects homosexual practice as incompatible with Scripture" and states that they "cannot advise the legitimising or blessing of same-sex unions nor ordaining those involved in same gender unions".

With at least six bishops attending the Conference this summer, who are themselves living in legitimised (and blessed) same-sex marriages, such a call is likely to ruffle a few feathers amongst those organising the agenda for the conference.

The Archbishop of Canterbury has already announced his decision that there will be no resolutions this year - instead there will be a number of thematic 'Calls' for global discussion.

Archbishop Justin Badi describes the GSFA as part of the "holy remnant that God has preserved" in the Anglican Communion. This may actually underestimate their significance.

Of the 1,000 bishops in the Anglican Communion who have been invited to the Lambeth Conference, approximately half serve in the GSFA churches, and between them they represent more than 75 per cent of Anglicans worldwide.

Their united voice might just be too loud for the Archbishop of Canterbury to ignore.