As a retired head of history, I feel the defunct O-level system was always palpably unfair towards girls. In fact, almost any linear examination system still is.
Most schools' examinations last more than a month. The natural cycle of a woman's menstruation means that she is inevitably going to be at a "health" disadvantage and thus an academic one, where a course is examined on a wholly linear basis. With the advent of modular exams, we are seeing a more level playing field for girls, though the public examination section of most subject courses still disadvantages woman.
David Ellis 128 Sandhill Street Worksop, Nottinghamshire