State immunity — Jurisdictional immunity — Underlying principles — Absolute theory of immunity — Foreign sovereign — Ownership of land in Malaysia — Writ issued against Queen in right of Canada in civil proceedings — Conditional appearance — Whether absolute immunity — Whether substituted service permissible — Effect of contractual undertaking as issue of immunity — Proper procedure for service of writ upon diplomats possessing immunity — Vienna Convention on Diplomatic Relations, 1961 — Diplomatic and Consular Privileges Ordinance 1957 — Diplomatic Privileges (Vienna Convention) Act 1966 — Civil Law Act 1956, Section 3 — The law of Malaysia