70.—(1) This section applies where—

(a) the tenancy (“the head-tenancy”) of the dwelling concerned is the subject of a sub-tenancy (“the sub-tenancy”), and

(b) the landlord under the head-tenancy proposes to terminate the head-tenancy.

(2) Where this section applies, a notice of termination in respect of the head-tenancy must, in addition to its complying with section 62, state whether or not the landlord under the head-tenancy requires the head-tenant to terminate the sub-tenancy.

(3) If a requirement to terminate the sub-tenancy is stated in such a notice, then, in addition to its being served on the head-tenant, a copy of that notice must be served on the tenant of the sub-tenancy (“the sub-tenant”) F164[by the landlord].