Does the Housing Act 1988 operate to make a long residential lease an assured shorthold tenancy if the rent exceeds £250 a year either at the outset or during the term of the lease?

As stated in Q&A: Could a lease which is a long lease be subject to the grounds for possession under the Housing Act 1988 by virtue of the ground rent rising in excess of £1,000 after a comparatively short period of time? If so, would a clause be effective which provides that even in the event that the lease is an assured tenancy at any time and there are ground rent arrears, the landlord cannot rely on ground 8 to recover possession?:

‘The requirements for an assured tenancy (AT) (including an assured shorthold tenancy) are set out in section 1 of the Housing Act 1988 (HA 1988). This provides:

“A tenancy under which a dwelling-house is let as a separate dwelling is for the purposes of this Act an assured tenancy if and so long as–

(a) the tenant or,