The decision was applauded by traditionalists and several primates overseas but infuriated liberals in the Church.

Although the Church of England officially objected to the legalisation of gay marriage and has opted out of performing the weddings, there have been growing signs of a more relaxed stance on homosexuality.

It is about to begin a process of discussion potentially leading to special services to bless same-sex relationships in Anglican churches - although the term "blessing" will not be used for theological reasons.

But the bishops ruled that although gay and lesbian parishioners can ask their priest for special prayers after their wedding, it will not be considered "appropriate conduct" for anyone in holy orders to marry someone of the same sex.

Anyone who defies the ban could face lengthy disciplinary measures. But one bishop has already said this might not mean being defrocked, suggesting they could potentially minister while defying the ban.

Rev Cain, the Vicar of St Mary with All Souls in Kilburn and St James in West Hampstead, announced his engagement to friends on the same morning as the bishops' decision emerged.

He told The Telegraph that not only will he press ahead with his plans but expects at least two bishops to be among their guests.

The couple, who are currently in the process of setting a date, also hope to have an informal celebration with Rev Cain's parish.

"We are hoping it will be early summer when the weather has improved but we are going to do it, there is no doubt about it," he said.

"We have been together for 14 years, we have waited a long time for the opportunity, I was there outside Parliament when the bill was passed so why wouldn't I?

"I wasn't planning to take a stand publicly quite honestly, I was just planning to get married, the bishops have made it an issue not me - I was just getting engaged which is my legal right."

The couple, who are currently abroad, previously exchanged rings and had their relationship blessed in an informal religious ceremony but chose not to enter a civil partnership as they were awaiting the chance to marry.

"For the marriage itself, if there is something it won't be a formal service in church," he said.

"But I am absolutely sure that both my parishes, which expressed great delight for me and Stephen after 14 years, will want there to be some sort of marking of our marriage with my parish.

"Which priest would get married and not celebrate with their parish?"

He said the ban had already damaged the authority of bishops.

"The bishops have really rattled people's cages," he said.

"It has frightened the clergy and some of them have said they are not going to get married, I know that a number of people have left the Church but I also know that a number of us are going to go ahead and deal with the consequences."

But he added: "They can't frighten me, the legal procedures for defrocking somebody are extraordinarily complex and expensive and very public ....to try to defrock someone simply for exercising their rights as a United Kingdom citizen would be extraordinarily bad publicity.

"I don't know what they are going to do - they are going to have to find some way of doing something to save face but without exposing the Church to further bad publicity, particularly after last year's debacle over women bishops and the trouncing we received in the media."

Meanwhile 24 academics and clerics, including some of Britain's foremost authorities on church history, have written to the bishops arguing that their pastoral statement, which banned gay priests from marrying, was based on a false reading of history.

The document claims that the introduction of same-sex marriage is the first time that there has been a divergence between the official legal definition of matrimony and that recognised in church law.

But the academics, including Oxford's Professor Sir Diarmaid MacCulloch, argue that the two definitions have differed in the past, most significantly in relation to divorcees who remarried.

END