The stark calculations were revealed during discussions at the Church's decision-making General Synod, which has been meeting in London, about ambitious plans to tackle declining numbers.

It is preparing to pump £72 million into a "reform and renewal" drive which includes plans to ordain 6,000 more clergy in the 2020s to build a younger priesthood which is less male dominated and less white.

The Archbishop of Canterbury has also initiated a major drive to win new converts.

But in a sobering assessment of the challenges parishes face, the Church's finance chief, John Spence, warned that attendances could almost halve in the coming decades.

Mr Spence, chairman of the Church's finance committee, said that current attendance figures suggest that an 81-year-old is now eight times more likely to attend services than an 18-year-old.

Currently around 18 in every 1,000 people in England regularly attend Church of England services -- a figure which includes mid-week and other special services.

But Mr Spence said that in 30 years time that proportion is likely to drop to 10 in every 1,000 -- or one per cent.

That rate of decline suggests that attendance at Sunday services across the whole of England would dip to just 425,000.

Recent figures published by the Church showed that Sunday morning congregations stood at 764,700, with total weekly attendances -- which include week-day services - just slipping below one million.

Mr Spence said that "on all likely measures of success" the demographic reality meant that the Church is unlikely to see net growth in the next 30 years.

"I could have given you other facts but I think you get the point," he said.

The new projections signal a dramatic deterioration in the Church's assessment of its own future.

Previously senior Church figures have spoken of the decline in numbers appearing to bottom out in recent years and, in an interview with the Telegraph earlier this year, the Church's General Secretary, William Nye, said the downward trend could continue for another five years.

Mr Spence said the Church's response should not just involve "bringing in a lot of managerial principles".

"This cannot and has never been about a numbers game it has to be about a holistic growth within the Church which is both numeric and spiritual," he said.

The Bishop of Sheffield, the Rt Rev Steven Croft, revealed that, in addition to the losses in the pews, around 70 per cent of the current body of clergy will have retired by 2030.

He said: "Should we simply accept that we will not have ministers of the right quality and background and therefore accept that retreat is inevitable?

"Of course not. We need to steadily, faithfully pray and work to call workers to the harvest.

"Should we simply accept that we will have fewer clergy in the future?

"By no means. We need courageously to seek vocations of all kinds in every place but especially among the young."

A spokesman for the Church of England said: "The reference to 30 years is based on projections which assume no change and underscore the importance of the renewal and reform programme.

"They do not factor in the changes being proposed.

"Most crucially, as the Archbishop of Canterbury said this morning, we trust in the grace and transforming power of the Spirit of God, who empowers and equips the church."

Earlier the Synod backed a motion calling for an independent inquiry into the impact of the way sanctions are imposed on benefit claimants.

Members gave a series of harrowing accounts of parishioners left relying on food banks because their benefits had been stopped because they had unavoidably missed or been late for appointments because of circumstances including bereavement or crime.

The former Tory MP Sir Tony Baldry called or the Church to lead an orchestrated lobbying campaign to put pressure on ministers to order an inquiry into the issue.

He told them: "From my 30 years of experience as a Member of Parliament, the most effective way of engaging with the system is actually to go and see your Member of Parliament at their constituency surgery.

"They can't escape, you're not going to get screened out by their researchers, they're not going to be able to give you a standard reply and they're going to have to do something.

"Actually, most members of parliament will treat with great respect a delegation from their local Deanery Synod or local clergy.

"You ask very simply for them to engage with the secretary of state to actually get this independent review.

"In practical terms, this is something everyone in this room can do and every Deanery Synod can do. And every Member of Parliament you go and see I guarantee will generate a personal letter from them to the Secretary of State, so that's quite a lot of correspondence that goes into the private office of the minister, and a number of them will take it further by asking questions in the House, tabling motions."

But one senior member of Synod said: "Renewal and Reform is known by some as Search and Rescue.

"There is too much of a sense of panic."

END