A vicar who allegedly had an affair with a married parishioner became the first member of the clergy to appear before a secretive new Church of England disciplinary tribunal yesterday.

The Rev David King, who has been suspended from his rural parish near Whitby, North Yorkshire, is accused of conduct “unbecoming to the office of the clergy”.

Mr King, a married father of three, is said to have engaged in a two-year relationship with Tracy Byrne, a local businesswoman and mother of four, which led to the break-up of her marriage. Mrs Byrne’s former husband, James, is the complainant in the case and has produced evidence including a saucy birthday card that Mr King allegedly sent to his wife.

If the allegation of adultery — which Mr King denies — is proved, the 55-year-old vicar faces a range of possible sanctions, including a lifelong ban from the ministry.

The case was heard in private yesterday at Leeds Crown Court at the start of a three-day hearing of the Bishop’s Disciplinary Tribunal, a new panel established to consider complaints of misconduct involving the clergy. It is the first case to go before a tribunal since a streamlined Church disciplinary process was introduced at the beginning of last year with the aim of dispensing quicker and cheaper justice to errant priests.

The new Clergy Discipline Measure brought to an end the medieval system under which churchmen accused of immorality had their cases heard by consistory courts. The process was criticised for being cumbersome, bureaucratic and very expensive, with each trial costing several hundred thousand pounds.

Fewer than five cases had been heard in the past 40 years, the most notorious in 1995 when the Dean of Lincoln, Dr Brandon Jackson, was cleared of having an adulterous affair with a female verger.

Such trials were heard in public. Although the Church has said that it wants the new disciplinary system to be transparent, it has ruled that tribunal hearings will normally be held in private. As a result, the press and public were not allowed to witness yesterday’s proceedings at Leeds Crown Court, which Mr Byrne, 52, travelled from his new home in Australia to attend.n He criticised the behind-closed-doors policy. “The need for the Church and any other important organisation to be transparent is obvious,” he said. “It undermines confidence if it appears to cloak itself in secrecy.

Mr Byrne, who was married for 20 years until his divorce in late 2005, complained to the Archbishop of York about the conduct of Mr King. He claimed that the vicar’s alleged affair with his 47-year-old wife, who runs a private care home, shattered any chance of saving their troubled marriage.

In his formal letter of complaint to the Archbishop, Mr Byrne alleged that his wife had confessed to the affair.

He said that he caught the couple “kissing and canoodling” on a couch in early 2004. Church officials were also handed the birthday card that was allegedly sent to Mrs Byrne by Mr King.

The picture shows a naked male pin-up. Inside are the words: “With very massive love to you today and every day. Dave xxxxxx.” A further message reads: “Am v. cross they used my photo without permission.”

Mr King, whose wife is a primary school head teacher, has previously denied any impropriety with Mrs Byrne. In his formal response to the adultery allegation last year, he said that he had known Mrs Byrne since 2001, insisted that their relationship had been “at all times professional” and denied behaving “in a way that is inappropriate and unprofessional”.

The vicar’s’s case is being heard by a five-strong panel. It is chaired by Geoffrey Tattersall, QC, chancellor of the diocese of Manchester, and also has two lay members and two members of the clergy.

The tribunal, which rejected yesterday an application for its proceedings to be heard in public, will reach its decision by a majority vote. Its findings will be made public.