Trapped in my school

Today I went to school like any other ordinary day. I normally teach 3 classes for a total time at my school of 2 1/2 hours on Mondays. Today, one of my classes was cancelled, which does happen from time to time. Not only is it a huge inconvenience for me because I generally miss a train and have to wait like an hour or so to get back home but all of my classes are in different spots of my lessons once one of 3 classes is cancelled. When I was told my class was cancelled, I asked the principal if I could stilll teach the class since it was just the teacher that was gone and not the whole class. The whole class does leave once in awhile for sailing or whatever other crap is more important than English lessons. Anyway, my mean, angry, old, bitter principal said no, I couldn't teach the class and, in addition, I wasn't allowed to leave school grounds until my normal time, meaning that I couldn't even leave early. Apparently, due to their ridiculous insurance policies, if I got hurt on my way to the train or whatever, it would falll back on them. I was considerably annoyed at this point. I asked if I could sign something releasing them from obligations but apparently not. Thus, I was obliged to sit in the office for about an hour, like a punished child, until it was my regular time to leave. I have never dealt with something so ridiculous or proposterous since living in France. I literally have never had more daggers shooting out of my eyes than today when the principal wouldn't let me leave. Now, obviously, I could have just walked out, I mean, what could they really do to me? However, because I was arguing with the principal, I missed one train so I had another hour to kill until the next train. Therefore, I just decided to sit in the office in the warmth, while I waited out the time until my next train. After about 15 minutes of me just staring at the secretary with nothing to do, I asked if I could use the computer in front of me. She said yes, of course. To put the icing on the cake, I thought it was funny that I wrote this post while imprisonned in the school.