Nothing in this Act contained shall restrain any corporation hereby empowered to grant leases and make grants as aforesaid from granting any leases, or making any grants, whether by way of renewal or otherwise, which such corporation might have lawfully and rightfully granted or made, either under the provisions of any public or private Act of Parliament, or under any other authority, or in any other manner whatsoever in case this Act had not been passed, or from taking any fine, premium, or foregift from the lessees in any renewed or new leases named or to be named, or from their under-lessees, or from any other persons having or claiming an interest in any such renewal, for any such renewed or new leases, save and except that in every lease (other than any lease granted under the powers of this Act) which shall be granted by any such corporation as aforesaid, of any lands or houses which shall have been leased for building or repairing purposes under any of the powers of this Act, there shall be reserved the best improved rent, payable half-yearly or oftener, which can be obtained for the same, without taking any fine, premium, or foregift, or any thing in the nature of a fine, premium, or foregift, for making or granting the same.