30.— (1) From the commencement of this Part, any—

(a) conveyance, or contract for a conveyance, of land held in a joint tenancy, or

(b) acquisition of another interest in such land,

by a joint tenant without the consent referred to in subsection (2) is void both at law and in equity unless such consent is dispensed with under section 31(2)(e).

(2) In subsection (1) “consent” means the prior consent in writing of the other joint tenant or, where there are more than one other, all the other joint tenants.

(3) From the commencement of this Part, registration of a judgment mortgage against the estate or interest in land of a joint tenant does not sever the joint tenancy and if the joint tenancy remains unsevered, the judgment mortgage is extinguished upon the death of the judgment debtor.

(4) Nothing in this section affects the jurisdiction of the court to find that all the joint tenants by mutual agreement or by their conduct have severed the joint tenancy in equity.