Subject to subsection (2) and without prejudice to subsection (3) of this section, no premises which are, or form part of, premises occupied by an Electricity Board shall be liable to be rated or be included in any valuation list or in any rate.
The foregoing subsection shall not apply—
For the purposes of the making and levying of any rate—
a hereditament of a rateable value calculated in accordance with the provisions of Part I of Schedule 7 to this Act.
The hereditament which an Electricity Board are to be treated as occupying in a rating area by virtue of subsection (3) of this section shall be taken not to be situated in any part of that area in which there are leviable, as an additional item of the rate, expenses which are not leviable in the area taken as a whole.
There shall have effect for the purposes of this section and Part I of Schedule 7 to this Act the supplementary provisions contained in Part II of that Schedule ; and in this section and the said Schedule 7—