Today's census for the North will indicate a Catholic population of around 44 per cent and a Protestant population of 53 per cent, according to well-informed nationalist and unionist sources.
The actual Protestant/Catholic breakdown, however, will indicate those who declare themselves as practising Protestants at under 50 per cent but when the community background figure is applied - i.e. were they brought up Catholic or Protestant - that figure rises to about 53 per cent, the sources said.
The census is expected to show a continuing trend of a rising Catholic population with a corresponding decline in Protestant numbers. For instance, the 53 per cent Protestant figure is 5 percentage points down on the 1991 census when the Protestant population was 58 per cent.
The 53/44 figure will provide some reassurance for unionists who were confronted with a number of recent media reports suggesting that the Catholic population would be as high as 46 per cent and the Protestant/unionist population would be under 50 per cent.
Such figures would have signified a dramatic rise in the Catholic population of 4 per cent in the 10 years since the last census, and an even more remarkable drop in the Protestant population of over 8 per cent. This would have essentially tallied with Sinn Féin's analysis that a united Ireland was achievable by 2016.
From a unionist perspective this would have meant that for the first time unionists were in a minority in terms of the overall population in Northern Ireland and that the disparity between Protestant and Catholic numbers had plummeted from 16 per cent in 1991 to less than 4 per cent now.
However, the sources said, the census will show the religious breakdown, based on community background, as rounding off at 53 per cent Protestant and 44 per cent Catholic, with the remainder from other backgrounds.
Mr Steven King, one of Mr David Trimble's senior advisers, contended that the trend of a faster rising Catholic population was tailing off. In any case, a significant number of Catholics would vote to maintain the North's link with Britain. "The deficiency of the 'count the Catholics' school of political science' is that it assumes Catholics are as homogenous in their political preferences as Protestants, contrary to all the available evidence.
"While Protestant support for the Union is almost universal, polls consistently find low (but statistically significant) Catholic support for the status quo," he wrote in his column in the Belfast Telegraph last night.
Writing in today's Irish Times, the Northern Secretary, Mr Paul Murphy, said he hoped the figures would serve as a reminder that "at the heart of the (Belfast) Agreement was a recognition that the bitter divisions of Northern Ireland will never be resolved by mere demographics".