The boundary is on a plan, not on the ground
Estate boundaries rarely follow anything visible. A lease line can run through the middle of a hardstand, along a fence that was moved years ago, or across an apron that looks like part of the road. Cleaning crews working from what they can see will either creep into the occupier's area or leave a strip that belongs to nobody in the scope. Both outcomes generate complaints, and neither is the crew's fault.
The only reliable approach is to read the site documentation and mark the boundary at the walkthrough. It takes one visit and it settles the question for the life of the arrangement. It also lets the estate manager answer an occupier's question about why a particular area is or is not attended, which otherwise becomes a recurring email exchange with no resolution. An answer that can be pointed to is worth far more than one that has to be reasoned out each time.
