The proportion of A-levels scoring at least an A grade has fallen for the first time in more than 20 years, according to official figures released on Thursday.
In total, 26.6 per cent of the exams were given an A or A*, down from 27 per cent in 2011 - a record drop of 0.4 per cent.
It is believed to be the biggest fall in the history of A-levels.
The last drop was between 1990 and 1991, when the number decreased to 11.9 per cent from 12 per cent.
Thursday's figures, published by the Joint Council for Qualifications (JCQ), also show that fewer A-level exams achieved an A* this year.
Around one in 12 exams were given the top grade, which is awarded for the third time this summer, down from 8.2 per cent in 2011.
Boys overtook girls at A* grade for the first time, with 8 per cent of boys' entries attaining the top mark, compared to 7.9 per cent of girls'.
The figures also show that the overall A* to E pass rate has risen for the 30th year in a row.
James Yates, headteacher at Lodge Park Technology College, has backed the hard work of his pupils, he said: "I think the students that are picking up their results today, they've had to work exceptionally hard to get the grades that they've got and I think they're probably as hard as they've ever been."