Mr Croker was the woodwork teacher at Ulvercote Elementary School. About half the children at his school signed up to the League of St Alexander, and Mr Croker was angry when it was reported that the headmaster Mr Willis would not be returning to the school. Soon after these events, Mr Croker went missing as well.
Mr Croker gave Malcolm Polstead some screws just before he went missing that couldn't be unscrewed. He said he wanted them in the hands of someone who appreciated them, as he was never going to use them, and thought he should give them away as he knew he probably wouldn't last much longer.