Mode of giving notice to owner or occupier of property.

When any notice is by or under this Regulation, required to be given to or served on the owner or occupier of any property and he is unknown, it may be given or served- (a) by delivering a written notice to some person on the property, or if there is no person on the property to whom it can be delivered, by affixing it to some conspicuous part of the property; or (b) by posting a pre-paid letter containing a written notice and addressed by the description of the "owner" or "occupier" of the property (naming it) in respect of which the notice is given, without further name or description.