Essery hadn't dressed up in an awfully long time, but there was something silly about the Halloween feast that made her want to show her students that school didn't always need to be so serious. Which is why she had shown up in costume (though what she was supposed to be was up for debate.)
As the choir finished performing, she stepped down from the stage that the Head Table area had been turned in to and congratulated all of them as they went down to join their classmates. They had been excellent - adequately creepy for the occasion. She couldn't have asked for more.