His face is thin and square-cheeked.
He is one of those people who is not good at staying still. His coat has a way of billowing out behind him when he moves, even when there's no wind.
He has big knobby hands, and long arms that always stick out too far from the sleeves. When he wears formal dress, his legs generally stick out too far as well.
Like all the staff at the castle, he is a powerful magic user. In addition to his tutoring duties, he does work for Chrestomanci in the tower workroom.
He has a tendency to get Enthusiasms, which dominate his dinner-time conversation and influence the decoration of the school room. In Charmed Life he has recently returned from a summer spent travelling to see artworks all over Europe, and the school room is decorated with posters of some of the artworks he went to see.
He has been known to read paperback books in French for fun.