Por the purpose of converting perpetually renewable leases and underleases (not being an interest in perpetually renewable copyhold land enfranchised by Part V. of this Act, but including a perpetually renewable underlease derived out of an interest in perpetually renewable copyhold land) into long terms, for preventing the creation of perpetually renewable leasehold interests and for providing for the interests of the persons affected, the provisions contained in the Eifteenth Schedule to this Act shall have effect.