Falling numbers of sixth-formers scored three or more top A-level grades this summer, official figures show.
One in eight students (12.5%) at all English schools and colleges achieved at least three A*s or As in their exams, down more than half a percent from 13.1% in 2011, according to Government statistics.
It is the first fall in at least four years, the figures show.
The Department for Education (DfE) data also shows that private school students are three times more likely to score top grades than their state-educated peers.
Almost a third (30.6%) of private school pupils achieved three or more A*-A grades, compared with one in 10 (10.7%) of those at state schools and 7.9% of those at further education colleges.
Overall, 91.7% of all students achieved two or more A-levels at grade E or higher, up from 94.1% in 2011.
And more boys than girls achieved three or more A-levels at grade A or higher (12.7% compared with 12.2%).