How many Catholics are there in Britain?
Pope Benedict XVI is the head of the biggest Christian denomination in the world, some one billion Roman Catholics, or one in six people. In Britain there are about five million Catholics, or about one in 12 people.
As he arrives in the UK for the first visit by a pontiff since 1982, what do statistics tell us about the state of the Roman Catholic Church in this country?
According to the 2001 census, there were 41 million Christians in Great Britain, making up almost three quarters of the population (72%). This group included the Church of England, Church of Scotland, Church in Wales, Catholic, Protestant and all other Christian denominations.
How this 41 million breaks down is harder to work out. The Church of England says about 26 million people have been baptised, the Catholic Church claims just over four million members in England and Wales - and another 695,000 in Scotland. Out of a total population of about 60 million, that means about one in 12 people in Great Britain is Catholic.
Figures for church attendance suggest both the Catholic and Anglican churches suffered a gradual fall in numbers up to around the turn of the century, but since then numbers appear to have more or less stabilised.
Numbers from the Catholic Directory suggest that currently about one million Catholics in England and Wales regularly attend mass. But according to the Catholic National Library, figures for mass attendance were not kept before 1989 and therefore no comparison is possible with the 1982 papal visit.
The Bishops' Conference of Scotland says an estimated 184,283 attended mass regularly in 2008. There's no equivalent figure for All Ireland - but the Catholic directory says there were an estimated 4.3 million Catholics living in Northern Ireland and the Republic of Ireland in 2008.
Figures for the number of men entering the priesthood show that after a fairly steep decline in the late 1980s and 90s, the numbers have begun to pick up again.
The Christian Research group which looks at trends in Christian faiths in Britain says numbers have stabilised in recent years - contrary to its claim in 2007 that congregations would continue to decline.
It seems numbers for the Catholic Church may have been boosted by an influx of immigrants - from Eastern Europe and Africa. While rural congregations have been dwindling, inner city churches have seen numbers rise.
The National Secular Society feels any boost in numbers will be shortlived. It estimates there will only be 101,700 Catholics attending church annually by 2050, compared to the current total of about one million.
Figures gathered by the National Centre for Social Research show that membership of most religions is lower now than it was 30 years ago, with a marked decline appearing among people who say they belong to the Church of England from 40 to 20%.
By comparison, the numbers of those claiming to be Catholic has remained fairly stable, dropping only 1% from 10 to 9% since 1983.
The number of people of all faiths attending church services appears to be at a low ebb, with 58% of those polled saying they never attend services.
But attendance does peak at Christmas. According to Church of England statistics, 35% of the population attend a Christmas service of some sort, rising to 42% in London.