International organizations — Immunity — Waiver — Whether submission to jurisdiction of English courts represented express waiver of immunity — Distinction between waiver of immunity from suit and waiver of immunity from legal process — Mareva injunction — Meaning of word “jurisdiction” — Interpretation of words and phrases where more than one possible meaning — Waiver of immunity not to be presumed — International Organizations Act 1968 — International Tin Council (Immunities and Privileges) Order 1972 — International Tin Council-United Kingdom Headquarters Agreement, 1972 — State Immunity Act 1978 — The law of England