Who needs buttons

As she stands there, frozen in place Miss Nolan hears a popping sound as another button falls from her shirt, and then another. To her horror she suddenly finds her shirt completely buttonless, one hand barely enough to keep the shirt closed over her bra, while the other keeps the clipboard firmly attached to her arse.

By now several students had begun to spot their assistant principle in distress, and more over several of them where pulling camera phones from their bags.

There's no way she can get away with standing here for too long without something hideous happening and she glances around the area, working out where she can possibly go for protection. She's right in the middle of the school yard, meaning she's half way between the school doors and her own car in the car park, but which of them would offer the safest protection?