State immunity — Jurisdictional immunity — Interpleader — Interest in property — Funds in escrow — State claiming title to proceeds of bank account — Whether State able to invoke State immunity to prevent proceedings going ahead — Control and possession of property through an agent or trustee — Stay of proceedings — Waiver of immunity — Whether a foreign State entitled to immunity after submitting to the jurisdiction of the courts of the forum State — Whether actions of third party capable of amounting to waiver — Whether third party acting as agent of the State — The law of Singapore