61.—(1) A reference in this Part to a particular period of notice to be given by the notice of termination concerned is a reference to such a period that begins on the day immediately following the date of service of the notice.

(2) A reference in this Part to the duration of a tenancy is a reference to the period beginning on the day on which the tenancy came into existence or the relevant date, if later, and ending on the date of service of the notice of termination concerned.