Re: Legal basis?
BBC Radio 4's PM programme took a light hearted look into similar situations from the past. On one occasion, an attempt was made to get an individual from an embassy to another country inside a diplomatic bag- which was actually a shipping crate. The plan failed because a mistake was made in the paperwork.
All this talk of diplomatic passports is making me think of the Goon Show...
Greenslade: Very good, sir. We present Baroness Orkesy's masterpiece, Baron Orkesy, or "A Strange Case of Diplomatic Immunity", in which a strange case of diplomatic immunity is recounted. Chapter One, a Strange Diplomatic Case of Immunity, or A Diplomatic Case of Strange Immunity, or through hook, line and blizzard with Ava Gardner.
Neddie Seagoon gets run over by a steamroller driven by Moriarty. Moriarty then explains that his steamroller has CD plates:
"Sapristi yakamacaca. Diplomatic immunity means I cannot be arrested, sued, disfranchised, blackballed, guillotined, run out, left in bulk, charged, hung, drawn or quartered, or needle-nardle-noo! You see, I happen to be the deputy vice pomfrit of the Titicacan delegation."