‘Hurry, Filch, hurry!’ shrieked Umbridge, ’they’ll be all over the school unless we do something–Stupefy!

A jet of red light shot out of the end of her wand and hit one of the rockets. Instead of freezing in midair, it exploded with such force that it blasted a hole in a painting of a soppy-looking witch in the middle of a meadow; she ran for it just in time, reappearing seconds later squashed into the next painting, where a couple of wizards playing cards stood up hastily to make room for her.

Don’t Stun them, Filch!’ shouted Umbridge angrily, for all the world as though it had been his incantation.

Right you are, Headmistress!’ wheezed Filch, who as a Squib could no more have Stunned the fireworks than swallowed them. He dashed to a nearby cupboard, pulled out a broom and began swatting at the fireworks in midair; within seconds the head of the broom was ablaze.