The property is actually a tenement flat, 1 floor up.
The cable which leads to the isolator enters the building via a hole above the flat door, this then runs along the hall ceiling, down to the skirting board, through the wall to the living room, up around the the door frame and then along an internal wall to the isolator.
On the opposite side of the wall from the isolator box is the bedroom.
I assumed, perhaps incorrectly, that the box could be moved to the other side of the door frame, closer to where the cable enters the room - is that incorrect?