Teacher threatening to leave my belongings outside?

This is probably going to come out as a general whine, but it's something that has really been bugging me for the past few weeks. In my school we have the KS3 locker hall in the middle of the school for years 7,8 and 9, KS4 year groups (10 + 11) each have their own locker halls, and sixth form have the sixth from centre off to the side of the school.
I'm currently in year 12, and ever since I’ve been at secondary school I've always left my bag and coat in the KS3 locker hall, because it has the most storage space (designated lockers for younger students, and wall rack for general bags and stuff), because it is the most central and the direct route to the dining hall from the classrooms, but ever since going to sixth form a new rule has been set up that sixth form cannot leave our bags, folders, coats or anything else on the racks on in this hall. They say we're supposed to put our stuff in the sixth from centre, but it's so overcrowded that it takes 10 mins to get in/out, and I'm worried about my belongings getting lost/broken if left in there, because it's so full.
Now, whenever a member of the sixth form tries to use the racks, this one specific teacher shouts at us to remove our stuff and threatens to put our stuff outside if we leave it here again. In my opinion, this is all incredibly silly, a pain for everyone involved and embarrassing. Take today for example I had just arrived at school and had placed my stuff on the racks to remove my coat and change my shoes. As I was about to leave (coat still on racks), this teacher screams at me from across the hall, causing the whole of KS3 to turn their attention to us, as she proceeds to yell at me that sixth form are not allowed under any circumstances to place belongings on the racks, and I had to remove it instantly or it would be removed and I would be escorted to the headmaster. Very calmly, I tried to explain to her that the sixth from centre is overcrowded and I don't feel comfortable leaving my things there, but she just kept shouting at me to remove my stuff. Eventually I had no choice to take my coat and walk off before she called the headmaster.
In my opinion, this rule is very silly and inconveniencing, we're not hurting anyone by placing out belongings in this hall, and I think this teacher is wrong to threaten to physically remove our stuff. Can she legally leave our things outside?
If anyone has an opinion, I'd be grateful to hear it!

I would suggest you go an talk to your headmaster about the problem explaining to him/her the circumstances (lack of space, too crowded...) and the worries you have about leaving your stuff in the sixth form center area (getting broken, stolen, going missing...). I am sure your headmaster would listen and do something about it, since that is what they are suppose to do.

...