A senior clergyman in the Church of England reportedly blocked from becoming a bishop because of his sexuality is apparently preparing to take his employers to court under the country’s equality law.

The Very Rev Dr Jeffrey John, the current Dean of St Albans, is understood to have hired Alison Downie, an employment and discrimination law specialist, to fight his case under the Equality Act 2010, which bans discrimination on the grounds of sexuality, The Guardian reported.

In 2003, John was forced to step down as the suffragan bishop (subordinate to a diocesan bishop) of the town of Reading after conservative evangelicals in the church raised objections. He was the first openly gay priest to be nominated as a Church of England bishop.

Two years ago, John was blocked from becoming the bishop of Southwark after the Archbishops of Canterbury and York intervened, according to a leaked memorandum written by a former dean of Southwark Cathedral.

The 59-year-old Dean is in a longstanding civil partnership with another cleric, the newspaper said. Church of England legal advice published in June last year says that a gay priest can be promoted to be a bishop provided they have not been sexually active during the priesthood. However, a selection committee can veto a gay candidate if “the appointment of the candidate would cause division and disunity within the diocese in question”, the advice adds.

Gay rights advocates within the church are pleased with John’s apparent move. “I think the Church has behaved appallingly towards him in particular and is continuing to behave appallingly towards its lesbian, gay, bisexual and transgender clergy and lay people in general,” the Rev Colin Coward, director of Changing Attitude, a lobby group in the Anglican Communion, was quoted as saying.

“It is time for the Church to be held to account for its abusive behaviour and its entrenched prejudice and homophobia.”

The Rev Rod Thomas, chair of the conservative evangelical group Reform, commented to the Guardian, “I think he knows that one of the things that bishops try to do is be a focus for unity and, hitherto, it has been clear that given the current controversies in the Church over sexuality, Jeffrey John would find that very difficult.

“Sexuality is a big issue facing the western world as a whole and the Church of England in particular, and while those issues are being debated and discussed, Jeffrey John is a figure that to some extent stokes the fires of controversy rather than finds a way through.”