Certain sub-tenants to become tenants on determination of tenancy.

When the interest of a tenant of any premises is determined for any reason, any sub-tenant to whom the premises or any part thereof have been lawfully sub-let and such sub-tenancy is subsisting on the date of commencement of this Act or where sub-tenancy is permitted by a contract between the landlord and the tenant, such sub-tenant shall, subject to the provisions of this Act, be deemed to become the tenant of his landlord on the same terms and conditions as he would have held from the tenant if the tenancy had continued.