People in teaching jobs have been urged to take on the IGCSE by an expert.
Writing for the Times, Ann Puntis, who heads University of Cambridge International Examinations, described it as "a wonderful qualification".
She said that staff in education jobs have often praised it to her for advancing students' accomplishments and making the classroom a better place.
Ms Puntis explained that the IGCSE is not modular and develops along with the needs of a school.
"The qualifications you take should be driven not by the type of school you attend but by the education that is right for you," she wrote.
Nick Seaton of the Campaign for Real Education recently gave an account of the benefits of the IGCSE.
He suggested more state schools take it up, as it would prepare youngsters better for A-levels and college.
Independent schools often use IGCSEs because they are viewed as tougher than ordinary ones.
Posted by Tim Colman