If at any time—
then, subject to subsection (2) below, the assured tenancy shall continue in existence as a tenancy held of the person whose interest would, apart from the continuance of the assured tenancy, entitle him to actual possession of the dwelling-house at that time.
Subsection (1) above does not apply to an assured tenancy if the interest which, by virtue of that subsection, would become that of the landlord, is such that, by virtue of Schedule 1 to this Act, the tenancy could not be an assured tenancy.
Where, by virtue of any provision of this Part of this Act, an assured tenancy which is a periodic tenancy (including a statutory periodic tenancy) continues beyond the beginning of a reversionary tenancy which was granted (whether before, on or after the commencement of this Act) so as to begin on or after—
the reversionary tenancy shall have effect as if it had been granted subject to the periodic tenancy.
The reference in subsection (3) above to the previous contractual assured tenancy applies only where the periodic tenancy referred to in that subsection is a statutory periodic tenancy and is a reference to the fixed-term tenancy which immediately preceded the statutory periodic tenancy.