IT will be difficult to compare exam results year-on-year because of planned changes to GCSEs, the headteacher of Bolton’s top performing school has warned.

At Bolton School, 99 per cent of the boys and 100 per cent of the girls made the grade in this summer’s GCSEs, with excellent performances in the numbers of young people achieving A* and As.

Bolton School is regularly among the top schools in the country.

Headmaster Philip Britton said: “The other feature of this year is that we are beginning a period of significant turbulence in exams, likely to last five years due to various reforms.

“Through the whole of that time, in reality it will be difficult to compare one year to the last.”

He added: “We must celebrate the achievements of each year group on their own terms, rather than make invalid comparisons between them.

“Employers and universities will have to be very careful in understanding the value of qualifications of various sorts through these years of change.”

Reforms due to come into effect next year are new GCSEs in English language, English literature and maths will be taught in schools and colleges. Nnew exams in other subjects will be introduced the following year.

The new exams will have new content and will be structured, assessed and graded differently from current GCSEs.

The Ofqual document outlining the reforms states: “The reforms we are announcing bring in the further changes that are needed if GCSEs are to become more engaging and worthwhile to teach and study, as well as more resilient and respected.”