Diplomatic privileges and immunities — Residences of diplomatic agent — Duty to protect against intrusion — Civil war in sending State — Premises in London occupied by representative of one faction in Nigerian civil war after departure therefrom of diplomatic agent — Occupier claiming possession as of right — Occupier evicted by police on executive instructions following diplomatic request for assistance — Whether premises at material time “private residence of a diplomatic agent” — Whether duty to protect applicable where ownership in dispute — Vienna Convention on Diplomatic Relations, 1961, Articles 22, 30 and 31 — Diplomatic Privileges Act 1964 — The law of England