I was thinking about the view from the back of The Lodge, the house in which it seems a witness lived. Walking back from the river, I used the wholly unscientific methodology of 'If I can see the window, the window can see me'. Obviously foliage changes from season to season and year to year, but I suspect the line of sight from the back bedroom window is something like the attached image. It's not panoramic, but coming from the direction of the river and abandoned buildings, you'd be in view for a period regardless of which exit you were taking either side of the (locked) car park.