State immunity — Jurisdictional immunity — Procedure — Service of process — Requirement that service of writ on foreign State be effected by sending documents to foreign ministry in forum State for onward transmission to foreign ministry of defendant State — Whether posting of writ directly to embassy of foreign State in forum State constitutes effective service — European Convention on State Immunity, 1972 — Submission — Whether application by foreign State to set aside judgment on grounds of immunity and non-compliance with procedures for service constitutes submission — The law of England