Rule 4 Where a claim form contains a claim for the possession of land, the Court may—
(a)if satisfied on an application without notice being served on any other party that no person appears to be in possession of the land and that service cannot be otherwise effected on any defendant, authorise service on that defendant to be effected by affixing a copy of the claim form to some conspicuous part of the land;
(b)if satisfied on such an application that no person appears to be in possession of the land and that service could not otherwise have been effected on any defendant, order that service already effected by affixing a copy of the claim form to some conspicuous part of the land shall be treated as good service on that defendant.