Census statistics, expected in December, may show the Catholic population of the North reaching 45 per cent or more. The data collected in 2001 is still being processed, but it seems universally accepted that a combination of higher birth rates, a younger population and a stark differential in death rates will point to a significant jump in the Catholic population.
Unionists claim that not all Catholics would vote for a united Ireland should a Border poll be called by the Northern Secretary. But the population trend indicates that if the union with Britain is to survive, it may do so in future years only with Catholic goodwill.
A BBC Northern Ireland investigation carried out for the Spotlight programme broadcast this week, said that of 15,000 deaths each year in the North, roughly 10,000 are Protestant and the remainder Catholic.
Dr Paul Compton, a demographer at University College London, told the programme that differentials in birth and death rates between the two communities could result in a Catholic majority within 30 years.
According to the Department of Education, there is now a Catholic majority among the under-16 school population.
Figures supplied to The Irish Times show that out of 341,965 children attending Northern schools, 173,254 or 50.66 per cent are Catholics, 146,103 or 42.72 per cent are Protestants and the remaining 22,608 are members of minority churches or are declared to be of no faith.The differential between the Catholic and Protestant totals has been narrowing since partition and the foundation of the State.
In 1921 the population breakdown was 66:33 in favour of Protestants, but the census data conducted last year is expected to show a significant closing of the gap, when results are analysed and published later this year.
Demographic trends suggest that a rise in the Catholic total is due to a combination of factors. These include a "working through" of a bulge in the Catholic birth rate in the late 1960s; stemming of emigration in general, and Catholic emigration in particular; and a trend among Protestants who qualify for third-level colleges to study in Britain and not return.
Corruption of previous census data is also a significant factor according to Dr Brian Feeney, a Belfast-based political commentator.
The censuses of 1981 and 1971 were unreliable, he says. "The 1971 census was flawed because of internment, the 1981 was flawed because of Sinn Féin, who organised the burning of census forms."
That census was carried out at the height of the Maze hunger strikes. Collection of completed forms in 1981 was also affected by the murder of Ms Joanne Mathers, a census form collector, in Derry in April of that year.
"The result was that the census of 1991 was the first correct census since 1961 and it made it look as if there had been a great leap in Catholic numbers. In fact the growth was fairly steady, it looks as if there has been a huge surge - but there hasn't."