Maths

There was a quite famous mathematician at Cardiff University in my day; can't remember his name but he was one of those guys who could do fantastically difficult numerical problems in his head as if he didn't have to think of them at all; he just spoke the answer straight out just after the question had been asked. Yet as regards the teaching of Maths there I am told there were many complaints: a group of students went to see him about the quality of the teaching in his department; he said, of course, that he would do something about and, of course, he never did. After he retired a rather brillant woman took over (Rosa Morris was it?); she had, it was rumoured, done some brilliant work on some aspect of flight during WW2. She was a rather grim person whom, you felt, you would never dare attempt to approach and while the teaching in her department was pretty awful no one was ever brave enough to approach her about it.
There were some lecturers in that department who were so dreadful that it was a wonder that they were employable at all. One youngish man (one of those blokes who you wondered if he'd ever know what it was to be young) used to start with chalk on the left hand side of the board in big letters and symbols and end up on the other side in letters and symbols so small you couldn't see them.
Another had a tiny book from which he read to us in a high-pitched voice, so high you had to be a dog to be able to hear it properly. Another, when asked a question, went off on a different track from that which he was on and lost everyone in the course of it.
I was told that he, when he later became professor of the department, took a phone call from a colleague after the xcolleague had been on holiday for about eight weeks and the conversation went somethig like this:
Colleague: Hello Professor, how are you?
Professor: Hah, it's you.... the answer is dee y, dee x squared plus 2 dee y dee x...... etc etc.
I wonder if the best mathematicians make the best teachers. In my experience they made the worst.