Bannister

Bannister, aka Big Bannister, was a member of "The Gang"; a group of bullies at the Experiment House school that Eustace Scrubb and Jill Pole also attended, in the autumn of 1942.

He was apparently known by his nickname as Big Bannister; so presumably he was either very large or very fat.

He most likely spent most of his time at school bullying other students, and talking to the Head-teacher of the school. Because the Head believed that children should be allowed to do what they want, Bannister and his gang were never punished for any of their antics, as the Head considered them to be 'interesting' psychological cases.

After their adventure in Narnia; Aslan sent Eustace and Jill back home, but also sent Caspian X along with them, so that when they returned to the school, they could give both the gang and the Head a terrifying fright, which they did.

Presumably, after the Head was fired from her position, Bannister and the rest of his friends were all expelled from Experiment House.