A schoolboy, Stan Locke, who did this is being punished by being completely isolated from all his classmates.
see http://www.bbc.co.uk/news/uk-england-somerset-31035847
Children's hair styles are no business of their schoolteachers, who should confine themselves to teaching their subjects.
While school attendance is compulsory such abuses of authority are likely to be common. I have long inclined to ending compulsion, so that heads will have to show enough respect and consideration for their pupils to persuade them not to leave.