Assured Shorthold Tenancy

[Barquentine]

If the Landlord has not served a 2-month notice requiring possession at the end of the fixed period in an AST, the AST has then expired and the day after that expiry the tenant has signed an agreement ("supplemental to and extending the previous Tenancy Agreement") but at a rent which is above the �25000 limit - does the Tenant then have an assured tenancy (because it cannot be an assured shorthold) - which itself will require a 2-month notice at the end of the extended term, or a common law tenancy determinable by a notice to quit?

[Twenty20]

You might be better posting this question on http://www.landlordzone.co.uk/forums/forumdisp lay.php?f=3