The Archbishop of Canterbury will perform traditional “dunking” baptisms at Malmesbury Abbey, in what has been described as “a genuine once-in-a-lifetime community occasion.”

Hundreds of people are expected to pack the abbey grounds for the outdoor baptisms in what is believed to be the first visit of an Archbishop of Canterbury to the 1,300 year-old site for centuries.

It had originally been intended for the Most Rev the Lord Archbishop Justin Welby to perform the ceremony in Biblical fashion, by immersing people in the River Avon.

But it was felt there were too many hurdles to overcome, including insurance, health and safety and mobility issues.

Instead, a portable baptistery will be installed for the ceremony on the afternoon of September 13.

Some 17 candidates from North Wiltshire will be baptised in the open air, weather permitting, during a three-day visit to the West Country by the leader of the Church of England.

Malmesbury Abbey curate the Rev John Monaghan said: “It’s fantastic. It’s going to be a great occasion.

“We originally hoped the baptisms would take place in the River Avon but there were too many difficulties.”

The Rev Christopher Bryan, priest in charge of the Gauzebrook Group of parishes around Malmesbury, said: “This is going to be huge. We are all looking forward to the Archbishop’s visit.

“The baptisms will be very dramatic. Those being baptised will stand in a large tank and be held as they topple backwards and go completely under in the water.

“They will be brought back up again; the Archbishop will probably help do this. It is all very symbolic of a new start, a new beginning.”

Mr Bryan added: “The Archbishop will be in Malmesbury all afternoon. It will be a big event at the abbey. There will be music and other things. It’s part of an incredibly busy three days in the Bristol Diocese.”

The 4pm ceremony is expected to last for two hours.

Churchgoers have been asked whether they would like to take advantage of an opportunity to be baptised in Malmesbury by the Archbishop of Canterbury.

Such a ceremony would “re-affirm the promises made at their baptism, when they were babies or young children.”

The Vicar of Malmesbury Abbey, the Rev Neill Archer, who is out of the country, wrote in his blog that the occasion would be a celebration of historic links between Canterbury and Malmesbury.

He went on: “It’s also a genuine once-in-a-lifetime community occasion.

“I’ve asked many of our local historians whether the Archbishop of Canterbury has visited Malmesbury in modern times and nobody can point to any visit at all in the last few hundred years, so this is a very notable event for the people of North Wiltshire.”