Are the black rubbish bins private property??

From an anonymous neighbor, a disturbing note was posted on our door. It claims that tenants in our building dump rubbish to the black 4 wheeled bin located on Montagu Row. From my understanding, these 4 wheeled black bins are for general rubbish from local neighbors. As we are on the corner of Montagu Row and Dorset, I don't see why we can't use these black bins. However, I wanted to be sure my understanding is correct. Are these bins only to be used for the residents of Montagu Row? Are these for a specific private building?? All of us in this building are considerate and mindful and we were shocked by this claim. Please kindly advise. (I had to choose "replace bin" as I had no other option but the 4 wheeled bins are just fine!)