"This agreement may be brought to an end (but not earlier than the expiry of the term certain) by the tenant giving to the landlord at least one calendar month's written notice."
"If an assured tenancy which is a fixed term tenancy comes to an end.....then.....the tenant shall be entitled to remain in possession of the dwelling house let under that tenancy and.....his right to possession shall depend on a periodic tenancy arising by virtue of this section."
"A periodic tenancy is one which continues from period to period until determined by proper notice."
"So there was, therefore, a surrender on that day."