4The tribunal shall have regard to and make an allowance in respect of any increased value which, in their opinion, will be given to other premises of the same owner—
(a)where the premises for which compensation is to be assessed are purchased under section fifty-seven of this Act, by the proposed re-development of the area in accordance with the re-development plan ; or
(b)in any other case by the demolition by the local authority of any buildings.