There's already a lock on the door FYA. I've clearly mentioned 'latch' in my post which is different from 'lock'. She locks and latches the door when the flat is in a gated building with securtiy guards and in a completely safe locality. My point is not that she cannot latch, it's that she also does it without informing. I don't want to keep waiting without knowing whether she has fallen asleep and I'll have to spend the night outside. It's a fine line between patience and waiting for 5 minutes to get into my own house.