I went to a school not dissimilar to the one written about in these pages and we went through our fair share of supply teachers. They all got laughed at. One was nearly crying after sitting on a broken table and falling on the floor after the whole class laughed at him. One stormed out the class never to be seen again. One cried his eyes out in a French class because he couldn't get help from staff on his mobile phone. On reflection this was silly behaviour but that's how supply teachers are treated and looked upon.
I didn't feel much sympathy for Mr. Chalk. Okay he shouldn't be treated like crap by his students but at the same time he wants to just do his job and go off home, he doesn't care about fixing the system or trying to help the students. And that was my experience with most supply teachers, there to do a job and go home. Makes me wonder whether Mr Chalk ever made an appearance at my school, he certainly sounds like quite a few of the supply teachers I had over the years.