Regarding the issue on the attire for Total Defence Day, only those who're involved in the Total Defence performance are required to wear No.4 on the day itself. Those who're not involved in the performance, you'll be wearing what you're being instructed to wear on the day by the school.
Hope this answers some of your question for those who came forward and asked me. And please do help to spread this message to the rest of your friends who're not aware of this instructions. Thank You.
C/OFFR Kelvin
To Serve with PRIDE and DEDICATION !