(1)Where in any lease of or comprising a mine of coal and subsisting on the vesting date there is contained a provision to the effect that—
(a)rent shall be payable thereunder in respect of coal carried away through the mine after being got from land not comprised in the lease ; or
(b)the amount of any rent payable thereunder, whether or not in respect of such coal as aforesaid, shall be ascertained wholly or partly by reference to the amount of such coal as aforesaid;
but being a provision applying only in relation to coal got from land for the time being in a different ownership from the mine, then, as respects coal got after the vesting date, the lease shall have effect as if the provision applied in relation to coal so carried away which has been got from all such land not comprised in the lease as was in a different ownership from the mine immediately before the vesting date.
(2)For the purposes of this section, a provision contained in a document varying or supplementing a lease shall be treated as if it were contained in the lease.
(3)This section shall be deemed to have had effect as from the vesting date.