The study of students in 21 grammar schools, published last week by the Equal Opportunities Commission, showed that only 29 per cent of pupils were from manual backgrounds.
Girls and A-level Science 1985 to 1995 suggests that working-class representation fell over the past decade, though the authors Tony Gallagher, Alex McEwan and Damien Knipe from Queen's University warn direct comparisons are problematic.
It is difficult to compare social class across the two studies in 1985 and 1995 because the method of classification changed. But with this reservation, the number of non-manual students soared by more than 300 (40 per cent), whereas manual numbers dropped by nearly 200 (30 per cent).
Sixth-form expansion benefited Catholics and girls most, but these changes hide important variations. The number of Catholic boys rose by a quarter, twice as much as Catholic girls. Protestant girls increased by another 17 per cent, but the number of Protestant boys declined because of a sharp drop in Protestant working-class boys.
Boys are still more likely than girls to study science at A-level, but the gap narrowed markedly over the past decade. The report argues that this is because girls see science as important for future employment rather than because of a change in attitudes to the curriculum itself.
Surprisingly, the improvement among girls was entirely on the Protestant side; Catholic girls actually studied slightly fewer A-level science subjects in 1995 than 10 years earlier.
"It is unclear why this has occurred, although our survey responses do suggest that girls in Catholic schools do not feel they receive as much encouragement to take science subjects as girls in Protestant schools," the authors comment.
Sex stereotyping remains at A-level. Last year girls made up 70 per cent of biology and 91 per cent of home economics students but less than one-third in physics, technology and design and computer studies. However, girls make up over half of chemistry students, partly because they see it as important for their chosen careers.
Girls have overtaken boys in science attainment at 16. In 1985, boys won higher average grades at O-level, but in 1995 girls were slightly ahead.
The report throws doubt on the argument that single-sex schools are better for girls than co-educational schools. At GCSE, girls in mixed schools last year took more science subjects than in separate schools, though there were no significant differences in attainment .
At A-level, girls in single-sex schools last year took slightly more science subjects than in co-ed schools. Boys in such schools are even more likely to be taking A-level science subjects than their contemporaries in boys' schools, and to perform better in GCSE.
"The evidence of this study suggests that pupils are more likely to take science A-levels in co-educational schools, and boys are more likely to achieve high attainment in such schools," the report says.
Girls and A-level Science 1985 to 1995 is available free of charge from the Equal Opportunities Commission for Northern Ireland, Chamber of Commerce House, 22 Great Victoria Street, Belfast BT2 7BA; tel 01232 242752 or fax 01232 331047.