11.—(1) When a ground rent is redeemed, all superior rents (if any) to which the land is subject are also redeemed or, where they are charged on other land as well as the land, are redeemed to the extent that they are charged on the land.
(2) For the purposes of this section that extent is to be taken to be a fraction equivalent to the ratio which the redeemed ground rent bears to the aggregate of that ground rent and the ground rents charged on the other land which are payable to the rent-owner.