47.—(1) Any document which is required or authorised under these Regulations to be served on a person may be served–
(a)by delivering it to that person;
(b)in the case of an incorporated company or body, by delivering it to its secretary at its registered or principal office, or by sending the document in a prepaid letter addressed to its secretary at that office; or
(c)in the case of any other person, by leaving it or sending it in a prepaid letter addressed to that person at that person's usual or last known residence.
(2) Where a document is to be served on the occupier of any premises under these Regulations and it is not reasonably practicable to ascertain the name and address of the person on whom it should be served, or the premises are unoccupied, the document may be served by addressing it to the person concerned in the capacity of “occupier” of the premises (naming them), and–
(a)by delivering it to some other person at the premises; or
(b)if there is no other person at the premises to whom it can be delivered, by affixing it or a copy of it to some conspicuous part of the premises.