The references in section 18A(6) to profits which would be taken to be attributable to the permanent establishment of a company in a territory include any income arising from immovable property which has been used for the purposes of the business carried on by the company through the permanent establishment in the territory (to such extent as is appropriate having regard to the extent to which it has been so used); and the references to losses in section 18A(7) are to be construed accordingly.