I was under him as a boy during the latter part of his teaching career when he was supposedly slowing down a bit. If he really was slowing down, the earlier period must have been incredibly active. He was a towering figure in my school days in every sense of the word. I use a quote from his autobiography as one of my signature quotes in e-mail:
I remain convinced that in a school, which is a large and complex organization, there must be one person at least of whom the boys stand in a certain amount of awe… the threat of being sent to him will be sufficient to cause apprehension.