The number of Church of England members who support same-sex marriage exceeds those who oppose it for the first time, according to a new poll. 

The poll shows a "significant shift in attitude over the last three years" and represents "a major challenge" for the Church's hierarchy, according to Jayne Ozanne, a leading gay evangelical Anglican and member of General Synod, who commissioned it from YouGov.

It was criticised immediately by conservatives.

Theologian and author Dr Ian Paul told Christian Today: "The polling doesn't tell us anything new—and is based on completely flawed methodology. Those 'who class themselves as Church of England' will presumably include the nominal Anglicans who never darken the doors of a church, so it is meaningless as a measure of what practicing Anglicans believe. Research in 'ordinary theology' also tells us that many 'who class themselves as Church of England' think Jesus was just a good man, and didn't die for our sins—I wonder if Jayne Ozanne thinks that is a reason to re-write the Creeds?"

He added: "The exercise reminds me of the vicar writing AWSL in the margins of his sermon notes: 'Argument weak; shout louder'. It is a shame that Jayne wants to completely by-pass the existing processes of discussion, as if the Church's historic, biblical doctrine of marriage can be dispensed with on the basis of an opinion poll—rather than by considering the actual theological issues at stake. If she were right, you would imagine that 'conservative' churches were full of grumpy old men, and not the many young people who are actually there."

According to the poll, 45 per cent of those surveyed who class themselves as Church of England believe same-sex marriage is right and 37 per cent think it is wrong.

YouGov polled 6276 British adults of which 1523 are living in England and stated a Church of England, Anglican or Episcopal affiliation.

Support for same sex marriage was even higher among younger Anglicans, with at least half of those under 55 and 72 per cent of those aged 25-34 in agreement. The lowest support was from Anglican men over 55, where just one in four said they believed that same-sex marriage was right.

The poll comes soon after the leaders of the Anglican Communion gathered at a Primates Meeting in Canterbury, where the Archbishop of Canterbury Justin Welby apologised for the hurt and pain the Church had caused to lesbian and gay people. The Primates also imposed "consequences" on The Episcopal Church of the US for consecrating gay bishops and approving same-sex marriage.

He said: "It's a constant source of deep sadness that people are persecuted for their sexuality. I want to take this opportunity personally to say how sorry I am for the hurt and pain, in the past and present, that the church has caused and the love that we at times completely failed to show, and still do, in many parts of the world including in this country."

A Church of England spokesman said: "The poll suggests an inconclusive breadth of view with less than half of Anglicans in England expressing support, a third opposed and a fifth uncertain. The process of shared conversations is continuing within the church, with general synod expected to be part of the conversation process in the summer. The Church of England is part of global Anglican communion which is mutually accountable for its teaching on marriage and other matters."