Section 30. Compensation for refusal of permission to build not to exceed difference between its value when it was refused and when it would have been granted.

When permission to erect any building has been refused under section 9 or 10, the amount of compensation shall not exceed the difference between the value of the land as determined by section 1[19B of this Act] 2* * * and the value which it would have had if the permission had been granted. In determining such value any restrictions to which the land is subject under any other law for the time being in force in regard to the right of person claiming compensation to erect a building on the land or otherwise to use, hold or dispose of the same shall be taken into consideration.