A British subject - living abroad and of foreign extraction - is arrested by the same foreign government and tortured. He's released without charge but no compensation is paid.
Another holder of a British passport has his house ransacked and burnt down because he is a Jew. The mob is egged on by the son of the foreign government's Minister of War.
How does the British government of the day respond? They remonstrate, demanding apologies and compensation. Then, eventually, when there is no acceptable response they send a dozen or so of the Royal Navy's ships of the line to blockade the ports of the foreign country in question and seize its shipping. Apologies and compensation are forthcoming.
This is a rough and ready description of what became known as the Don Pacifico affair of the mid-nineteenth century. The foreign country in question was the newly-independent Kingdom of Greece. The driving force on the British side was the sometimes jauntily reckless Foreign Secretary Lord Palmerston (below) - exponent of 'gunboat diplomacy' - who stated in the Commons debate on the affair:
As the Roman, in days of old, held himself free from indignity when he could say Civis Romanus Sum, so also a British subject, in whatever land he may be, shall feel confident that the watchful eye and the strong arm of England will protect him against injustice and wrong.
But the issues were a lot less black and white than I've painted them. The expropriation of the expat was conducted legally. The tortured British subject was from the Ionian islands, a British possession at the time, the inhabitants of which were shortly to rebel and be duly flogged by their British masters. Don Pacifico, the Jew, was arguably Portuguese rather than British, something of a fraudster and his claim for compensation was exaggerated. The aggressive British response was motivated as much by international political rivalries and sovereign debts unpaid as by the desire to secure justice for British subjects. It was also a rather ridiculous adventure: as Palmerston's most recent biographer puts it 'bluster has no sense of proportion'.
Certainly, a storm of controversy at home and abroad descended on Palmerston's head as a consequence of his orders. Gladstone's reply to Palmerston's claim above did what the British liberal is supremely good at - seeing things from the other side:
What then, Sir, was a Roman citizen? He was the member of a privileged caste: he belonged to a conquering race, to a nation that held all others bound down by the strong arm of power. For him there was to be an exceptional system of law; for him principles were to be asserted, and by him rights were to be enjoyed, that were denied to the rest of the world. Is this, then, the view of the noble lord, as to the relation that is to subsist between England and other countries?
Nevertheless, I can't resist admiring what Palmerston did back then - such confidence and certitude in what it meant to be a subject of the Crown. What's more, doesn't the episode cast a dispiriting light on the plight of British subjects in Zimbabwe; the torture inflicted on British subjects and residents as described in this recent post, potentially with their own government's connivance; and the kidnapping and sometimes execution of British hostages in Iraq and elsewhere over the years?
The Foreign Office's standard modus operandi when presented with an injustice (or worse) perpetrated on a British citizen appears to be to talk softly, ensure the other side doesn't lose face, steer clear of any suggestion that there might be an aggressive response and ultimately not to respond aggressively anyway, whatever the outcome. The patient negotiation and firm persuasion of soft power: a sensible strategy for much of the time, I'm sure. But, once in a while, wouldn't it be a good thing to see the modern equivalent of a gunboat deployed to protect British citizens?