The placement of the rug is always a matter of personal taste but also one of function. In this case, the rug was placed as a grounding for the furniture and the slate flooring was to remain exposed in the area in front of the radiator for purposes of keeping the rug clean (not to track in dirt from the garden) and as well the window itself on the left side of the photo swings open therefore the seating is going to be more on the other side thus the purposes of the location.