According to the Brighton Evening Argus the headteacher, Adrian Marshall, and some parents complained the police performance was insensitive and frightened the children.
"At the end of the day, he was a wanted person," replied North Brighton Sector Sergeant Ken Atkins.
"They were not aware of the Christmas concert but because it was a school, officers treated the situation sensitively."
They waited outside for the man to appear. But when they asked him to come quietly, he ran into the school hall. He was later jailed for four months.