Almost a quarter of the grades received by Oundle School students were A*s in this year’s results.
Headmaster Charles Bush said the results represented a ‘tremendous’ effort by pupils and teachers.
He added: “We are proud of these achievements and grateful for the academic leadership shown by this group of pupils during their time at school.
“They deserve real congratulations on their success which has set up some wonderful opportunities for their tertiary education.”
Among the top achievers were Jess Varley, 18, from Fotheringhay near Oundle and Henry Li, 17, a boarding pupil from Hong Kong, who each achieved five A* grades.
Overall, 89 per cent of pupils achieved A* to B grades, with over 60 per cent of grades either A* or A.
The school said 16 of its pupils have secured places at either Oxford or Cambridge University.