Lord Williams’s School GCSEs results dipped as 55% of students achieved five or more A* to Cs including English and Maths.
This represented a 10% fall compared to 2012 but nationally school results were expected to drop for a second year running as key subjects are made tougher.
Headteacher David Wybron said: “I want to acknowledge the wide range of achievements of our students.
“We are in very turbulent times in terms of examination results and year on year we are dealing with puzzling results.
“The dip in results is not a surprise, however unwelcome, because we were aware of late changes in grade boundaries in some subjects which mean that some students have been awarded lower grades than their marks would have earned them last year.
“In one core subject the pass mark for a C grade has moved by 6.5% on last year. We will know more once we receive the results of remarks.”
The following students gained at least 7 passes at grade A* or A: Elijah Andrews, Jimmy Austin, Ruairi Baker, Jessica Baldwin, Jasmine Bernard, Olly Bevan, Rebecca Brightling, Alyssa Brown, Lina Budde-Manning, Ella Burgess, Jess Burman, Conor Champion, Laura Cooper-Smith, Rebecca Daly, Daniel Hambly, Dominic Kelsey, Emily Keogh, Josie King, Miriam Malein, Charlotte Mann, Michelle Poalses, Emma Ralphs, Josie Richards, Charlotte Rogers, Eleanor Shearwood, Ewan Sheen, Hannah Smith, Mary Walters, Brendan Ward, Benjamin Warwick, James Wooster.