There is an acknowledged difficulty in demonstrating that the standard of school exams remains constant over the years. It is a source of debate every summer when exam results come out. There is some evidence that foreign language exams, and French in particular, have declined in standard since the 1980s, but empirical measures to demonstrate this objectively are rare. This paper describes a measure of lexical difficulty which has been applied to reading comprehension texts taken from A level, O level and GCSE exams delivered through the 1980s and 1990s. It shows that this calculation is a workable measure of comparative difficulty in the texts used in exams, and therefore of standards across time. More interestingly, it shows that O level texts are lexically harder than current GCSE texts and this supports other evidence that GCSE French is a linguistically easier exam than its predecessor. (Contains 2 tables, 4 figures, and 1 note.)