A school warned parents that any 15 and 16-year-olds turning up from Monday with “false eyelashes or false nails” will be “isolated” which could affect their exam grades.

Assistant head Dave Saunders, part of the eight strong leadership team at Marshland High in Wisbech, warned in an email that Year 11 students must comply with the school’s behaviour policy.

He reminded parents that “students are prohibited from wearing false eyelashes and false nails.

“Students also need to be in appropriate footwear.

“If your child has false eyelashes or nails, they will need to be removed by no later than Monday May 24. Any student not complying with behaviour rules will be isolated until the situation is resolved.”

He emphasised how “proud I am of our year 11 students” and that despite the “the very challenging circumstances linked to Covid-19, the students have shown resilience, responsibility and perseverance towards their education”.

Mr Saunders also accepted it was “a very stressful time for students” as they complete assessments ahead of GCSE grading.

“Staff are working tirelessly to give our students every opportunity to demonstrate their knowledge and skills to achieve the grades they deserve,” he said.

Students’ final day in school is Friday June 18, he said, which means that in the weeks before “every single lesson counts towards your child’s GCSE grades.

“Therefore, it is imperative that all students set themselves a target of 100 per cent attendance for the next four weeks.

“If students are in isolation due to their behaviour or for not meeting school expectations, it will have a detrimental effect on their grades.

“They will not be able to complete their assessments under the same level of control as students participating in lessons.”

A parent who contacted this newspaper fears that if the school fails to relax its hard-line policy, it could have a serious effect on the futures of its pupils.

Headteacher Craig Jansen said that behaviour is "categorically not used in any way to make any judgement on any student's centre assessed grade.

"The school is precisely following the Joint Council for Qualifications' guidance for the determination of students' centre assessed grades.

"Teachers are only using student work produced in line with the Joint Council for Qualifications and exam board guidance."

Mr Jansen added: "All teachers have undergone training on determining grades to ensure consistency and fairness to all students. This includes objectivity and unconscious bias training.

"Marshland High School has a proud reputation for high expectations of its students and for excellent student behaviour."