skinney school trousers

My son was also told today that no skinny fit trousers would be allowed and are seen as inappropriate school wear, my son himself wears trousers bought from the school shop near the mall in town centre wich cost £16 a pair and are in no way skinny fit at all he has been told that the head will be measuring the bottoms of trousers to make sure they comply with her new rule, my son has always been above average in every subject up untill the new head taking over and silly rules been put in place for things wich do not affect children's learning what so ever ie not having a black and blue pen because he only had a blue pen half hour detention he has now just lost all interest in learning and it is effecting his grades I spoke to the head whos answer simply was if you don't like it you can always move him school she was rude and very patronising and since has been no help at all things have just gotten worse!! Anyway back to the petition at hand why does what type of trousers they wear affect there learning my son has been excluded 7 times since the new head started but not once before she started what does this tell you the need a new head and a new attitude