(1)On and after the valuation date no term of years in coal or a mine of coal shall be capable of being created either at law or in equity by way of underlease out of a term of years therein :
Provided that this subsection shall not apply to the creation as aforesaid of a term of years by way of mortgage or pursuant to a lease consolidation scheme made under section twelve of this Act, or to minerals or substances that are subsidiary coal hereditaments within the meaning of section six of this Act or to a mine thereof.
(2)In every lease granted by the Commission there shall be implied, and every coal-mining lease the immediate reversion whereon is vested in the Commission by virtue of this Part of this Act, either as to the whole or as to part of the premises comprised therein, shall have effect as from the vesting date as if it had contained, a covenant on the part of the lessee or of the lessees jointly and severally, as the case may be, not to assign or to part with the possession of any coal or mine of coal comprised therein without first obtaining the written consent of the Commission (which may be withheld without reason given and at the sole discretion of the Commission), and a condition of re-entry in the event of a breach of the said covenant:
Provided that, where such a lease as aforesaid comprises premises the immediate reversion wherein is vested in the Commission and other premises, the condition of re-entry shall extend only to the first-mentioned premises.
(3)The covenant mentioned in the last preceding subsection shall have effect as a covenant to which section seventy-nine of the Law of Property Act, 1925, applies and which does not contain any such expression of contrary intention as is therein mentioned.