Colin Wall is the deputy headmaster of Winterdown and husband of guidance counselor Tessa Wall. He is the father of Fats Wall. He suffers from obsessive-compulsive disorder and has an extreme fear of being accused of child molestation. He tried commit suicide after he and Tessa adopted their son, because he was so afraid that he would accidentaly hurt him.

Fats exploits his greatest fear by posting on the Parish Council website that Colin fantasizes about molesting children and that "the Ghost" does not know whether or not he has actually done it.