At dawn on Sunday "a light naval division" of the Kingdom of Patagonia (a yacht containing an undisclosed number of French adventurers and romantics) landed on the Minquiers islands south of Jersey.
The invaders hauled down the Union flag and replaced it with the blue, white and green standard of the spoof (but not entirely spoof) Kingdom of Patagonia, re-establishing a claim first made in 1984.
The capture was revealed in a faxed communique to Reuters news agency in Paris yesterday. The statementclaimed the uninhabited rocks - officially British since 1953 - on behalf of the "government of His Majesty Orelie- Antoine I, King of Patagonia".
King Orelie-Antoine was a French explorer and idealist who was proclaimed king of Patagonia, at the tip of South America, by the native population for a few weeks in 1860, until the Chileans saw him off. He has been dead for 130 years.
The instigator of the weekend's action is the self- proclaimed consul general of the Kingdom of Patagonia, who claims about a thousand adherents. His name is Jean Raspail. He is a 73-year-old French royalist, travel-writer, philosopher and practical joker.
Mr Raspail is, in almost all respects, a serious person. He is a chevalier of the Legion d'honneur, the highest French civilian honour. He has a four- inch entry in the French edition of Who's Who.
Speaking on the phone yesterday from his home in Neuilly-sur-Seine, west of Paris, he said: "This is a game but it is a game played seriously in the way that children's games are played seriously. We will present the British flag we took from the islands to the British ambassador in Paris in due course."
By claiming the Minquiers rocks, half way between Jersey and the Breton coast, Mr Raspail and his followers wish to make two points. They wish to challenge the "unacceptable and prolonged" British occupation of the Falkland Islands (properly part of Patagonia, they claim).
And they wish to keep alive the French claim to the sovereignty, and rich fisheries, of the Minquiers archipelago, a source of contention between the two countries for 200 years, until awarded to Britain by the international court at The Hague in 1953.
The last landing made by the "Patagonians" on the rocks in June 1984 - when Mr Raspail commanded the fleet personally - caused a brief stir in Britain.
The Government and the press took the incursion seriously (the 1982 Falklands war being then fresh in the public memory). The latest invasion comes at the time of a fisheries dispute with French trawlermen in Channel Islands waters.
"Our action is symbolic but the cause is real and just," Mr Raspail said. "The French government has cravenly dropped its claim to these rocks, which are properly French."
But why claim the islands in the name of a fictional kingdom? "King Orelie- Antoine was a dreamer. A little crazy, probably. We wish to keep alive the dream."
The invaders left another claim to sovereignty, besides their flag. The main island, the only part of the Minquiers group to remain above water at high tide, boasts three or four buildings, including a toilet, for the convenience of visiting yachtsmen. It carries a sign saying: "This building is the southernmost building in the United Kingdom".
On Sunday, the French/ Patagonian claimants placed another sign above the first, reading in French: "This building is the northernmost building in the Kingdom of Patagonia".