According to provisional figures released by the Independent Schools Information Service (ISIS), 48.2% of all exam entries from 600 fee-paying schools were graded A* or A, up from 45.2% last year.

The overall national average in the results released last week was 14.7%.

More than one entry in six received an A* grade. The national average is less than one in 20.

And 93% of candidates achieved grades A* to C, up from 92% last year. The national average is 54.7%.

Broader spread

King Edward VI High School for Girls in Birmingham performed best among the independent schools.

The school - with fees of £4,725 a year - comes out top of a list of 600, using a new measure of performance which the government is introducing for all schools.

This uses a points system, from eight for an A* to one for a G grade, to produce an average point score per pupil, however many exams they sat.

It is intended to reflect a broader spread of achievement than counting the proportion of candidates getting at least five A* to C grades.

ISIS says that under the old system, Eton College would come top - it is 30th in the new system - and King Edward VI's Girls School would be 93rd.