Top scorers overall were in Northern Ireland, where nearly a quarter of students got A-grades in the old-style A-levels, compared to nearly one in five in Wales and just over 18 per cent in England.
The province's pupils are also racing ahead in the new AS-levels, with 28 per cent getting grade As compared to 16.5 and 16.8 per cent in Wales and England respectively. They also did better across the full A to E grade range, marginally beating the Welsh pass rate at A-level (92.1 to 92 per cent) and more than six percentage points ahead of the English with their AS pass rate (92.5 to 86.4).
But girls in Wales are also making their mark at AS - the proportion of girls getting A grades was four percentage points higher than their male classmates. Girls outperformed boys in all three countries.
In Scotland, education chiefs avoided a repeat of last year's exams chaos by getting 99.7 per cent of Highers results out to thousands of students this week.
But officials from the Scottish Qualifications Authority had to make a humiliating apology, after over-estimating the improvements in Higher performance.
Their initial claim of a 7.1 percentage-point increase in pass rate over last year was reduced to a more credible 1.3 points, after education minister Jack McConnell asked the authority to check its figures. The Higher exam pass rate was 72.4 per cent.
Last year, only 88 per cent of results in Scotland were delivered on time, leaving hundreds of students at risk of missing university places.
The political fall-out led to a shake-up of the agency, and the departure of its chief executive Ron Tuck. This time, his successor, Bill Morton, personally telephoned some youngsters to check that they had received their results, and millions of pounds were spent shoring up the system.