State immunity — Head of State immunity — Waiver of immunity — Wardship proceedings involving children of ruler of sovereign State — Ruler of sovereign State seeking orders for return of children — Ruler of sovereign State offering assurances of future conduct — Ruler waiving immunity in respect of enforcement of any orders to be made in proceedings — Whether waiver effective — Consequences of waiving personal immunity before State courts — Immunity of State property

Diplomatic relations — Diplomatic assurances — Weight of diplomatic assurances in domestic courts — Wardship proceedings involving children of ruler of sovereign State — Ruler of sovereign State seeking orders for return of children — Ruler of sovereign State offering assurances of future conduct — Whether assurances providing protection for children from risk of abduction — Whether enforceable in event of breach of any order made — Withdrawal of assurances — Consequences of withdrawal — The law of England