State immunity — Head of State — Immunities — Dignity of Head of State — Duty to respect and protect dignity — Whether King of Saudi Arabia immune from suit by claimant alleging she was his estranged wife — Whether court correctly exercising discretion to afford King protection from scrutiny and comment — Private hearings — Whether claim to sovereign immunity public claim demanding open litigation — Private acts — Boundaries of immunity — Legitimate public interest — Protection of identity of sovereign — Whether legitimate ground for imposing reporting restrictions — Respondent to respond to appeal in open court — Whether breach of Vienna Convention on Diplomatic Relations, 1961, Article 29 — Diplomatic Privileges Act 1964 — State Immunity Act 1978 — The law of England