As Britain prepares for a visit from the Pope, there is opposition from some gay people who believe the Roman Catholic church is intolerant of their sexuality. But in one London church homosexuals are attending a "gay Mass" with the blessing of senior clergy.

Paul Brown had not been to church since his mother's funeral in 2002. Now he is back in the pews, courtesy of a Mass for lesbian and gay Catholics which is the only one of its kind in the UK.

"I searched for a Mass with a positive message about things you should do, not someone telling me all the things I shouldn't do," he says.

Paul, who sports a black leather biker's jacket, is one of a number who have transformed the church of Our Lady of the Assumption and St Gregory in London's West End.

They sing hymns at the top of their voices. Many are aged under 30. Some have dyed hair. Suddenly, Catholicism seems be all the rage in this part of central London .

If you think this is a bit strange - well, it is. Catholic Church teaching on homosexuality is tough. Lesbian and gay Catholics are called to live chaste lives.

The only sexual expression allowed by Rome is marriage in which all sexual acts are open to the transmission of new life, hence the ban on artificial contraception.

My life without the Soho Mass would be bleaker, lonelier and less joyful. Renate Rothwell

So how has a "gay Mass" come about? (It is, in theory, open to all-comers, but this is what it has come to be called.)

"People had been used to meeting at the nearby Anglican Church of St Anne's and there was a feeling that it was time to find a way of finding Catholic premises," says Monsignor Seamus O'Boyle, the parish priest.

A series of draft documents were passed between top-level Cardinals in Westminster and the Vatican, to agree some basic ground rules.

The Church hierarchy wanted assurances that the services would not become a platform for challenging Catholic teaching. So one of the "underlying principles" of staging the service is: "Information about the Mass will be sensitive to the reality that the celebration of Mass is not to be used for campaigning for any change to, or ambiguity about, the Church's teaching."

'Homosexual lifestyle'

Organisers behind the Soho Masses Pastoral Council, the team that organises the services, are happy to accept these conditions.

THE POPE'S BRITISH DIVISIONS Hear the full programme on BBC Radio 4, Thursday 9 Sept at 0900 BST, repeated at 2130 BST. Or listen again on the website The Pope's British Divisions

"This is not a place which offers a platform for voicing criticisms of church doctrine," says the council's chairperson Joe Stanley.

"The emphasis is on pastoral care. Sometimes people come here and have tears in their eyes, because for the first time, two really important parts of their lives have come together: their Catholicism and their sexual identity."

Renate Rothwell is another stalwart. "My life without the Soho Mass would be bleaker, lonelier and less joyful," she says.

This mass is the only one of its kind in the UK, so far.

Asked by the BBC if there was any reason why similar masses should not be introduced up and down the country, Archbishop Vincent Nichols, the leader of the Catholic Church in England and Wales, said: "I think that's a judgement for a bishop and it's a judgement in response to a pastoral need."

Anybody who is trying to cast a judgement on the people who come forward for communion really ought to hold their tongue. Archbishop Vincent Nichols

In other words, if other gay Catholics ask for the same in Manchester or Brighton, it might be considered.

But not all are happy in the Catholic family. Twice a month a small group of traditionalists line the pavement opposite the church.

They pray the rosary on their knees, sing hymns and have petitioned the Archdiocese of Westminster to scrap the Mass.

They are backed by former Catholic Herald editor, William Oddie, who has accused church leaders of supporting those who engage in what he calls "the homosexual lifestyle".

"The fiction which justifies the archdiocese in its support for the Soho Masses is that they are celebrated for the benefit of gays who accept the teachings of the Church and therefore refrain from any form of sexual activity," he has written on his blog.

Immigration

But Archbishop Vincent Nichols says he continues to support the Mass.

Watch Peter Marshall's film in which he visits the Soho Mass on Newsnight on Thursday 9 September 2010 at 2230 BST on BBC Two, then afterwards on the BBC iPlayer and Newsnight website BBC iPlayer Newsnight

"It is a parish mass to which everybody is invited, but it has a particular appeal to people of a same sex orientation - not to distinguish them from the rest of the congregation, but to say you can be at home here.

"And I think that's the right thing to do because it offers slowly, and it is slow, a chance for those who as it were feel they live under a great pressure of an identity to perhaps shake that a bit looser and to say no, first of all I'm a Catholic and as a Catholic I want to come to Mass."

And in a hard hitting riposte to critics of the mass, the Archbishop says "anybody who is trying to cast a judgement on the people who come forward for communion really ought to learn to hold their tongue".

In 1982 at the time of the last papal visit, such a mass would have been the stuff of fantasy. But the Catholic Church in Britain has undergone widespread transformation since the visit of John Paul II.

Whether it is immigration from Eastern Europe, the rising tide of secularism, the public image of priests and the hierarchy over the abuse crisis and the advent of married Anglicans into the ranks of the clergy: this is a faith community in the melting pot.

Some see this as an opportunity while others resist change. On the eve of Pope Benedict's visit, that is what makes the four and a half million UK Catholics so fascinating.