“(3) Any notice required or authorised by this Act to be served shall be sufficiently served if it is left at the last-known place of abode or business in the United Kingdom of the lessee, lessor, mortgagee, mortgagor, or other person to be served, …. (4) Any notice required or authorised by this Act to be served shall also be sufficiently served, if it is sent by post in a registered letter addressed to the lessee, …, by name, at the aforesaid place of abode …, and if that letter is not returned by the postal operator (within the meaning of Part 3 of thePostal Services Act 2011 ) concerned undelivered; and that service shall be deemed to be made at the time at which the registered letter would in the ordinary course be delivered. (5) The provisions of this section shall extend to notices required to be served by any instrument affecting property executed or coming into operation after the commencement of this Act unless a contrary intention appears.”
“If the notice is sent by post, it must be addressed to a tenant at the dwelling unless he has notified the landlord in writing of a different address in England and Wales at which he wishes to be given notices under this section (in which case it must be addressed to him there).”
“Thus a former address will only be the “last known” address if the server of the notice has taken reasonable steps to find out what the intended recipient’s current address is. What he would have found out on making reasonable enquiries will be knowledge imputed to him.”