4Where a notice is to be served on a person as having an interest in, or as the occupier of, land and the person's name or address cannot be ascertained after reasonable inquiry, for the purposes of this Act the notice may be served by—

(a)addressing it to the person by name or by the description of “owner”, or as the case may be “occupier”, of the land (describing it), and

(b)leaving it either—

(i)in the hands of a person who is, or appears to be, resident or employed on the land, or

(ii)conspicuously affixed to some building or object on the land.