Summary.1,439 boys, members of four public schools, took Test AH6 AG. This is a high‐level test of reasoning whose total score can be broken down into a verbal (V) and a numerical‐plus‐diagrammatic (N + D) subscore. These three measures were compared with the boys’ GCE results at O‐level and A‐level.Significant correlations were obtained between the test and GCE, for most school subjects. A tendency was found for V to yield the best results in arts subjects; in mathematics and science, however, total score in general yielded a closer association than did N + D. AH6 AG proved to be a good predictor of all‐round scholastic ability on the criterion of number of O‐ and A‐level subjects s