Where the period for which in accordance with the provisions of Part II of this Act it is agreed or determined by the court that a new tenancy should be granted thereunder will extend beyond the date on which the interest of the immediate landlord will come to an end, the power of the court under Part II of this Act to order such a grant shall include power to order the grant of a new tenancy until the expiration of that interest and also to order the grant of such a reversionary tenancy or reversionary tenancies as may be required to secure that the combined effects of those grants will be equivalent to the grant of a tenancy for that period; and the provisions of Part II of this Act shall, subject to the necessary modifications, apply in relation to the grant of a tenancy together with one or more reversionary tenancies as they apply in relation to the grant of one new tenancy.