London — Three of Britain's imperial chickens have come home to roost at Westminster simultaneoulsy -- and now they are about to be joined by an imperial albatross. The chickens are all British colonies whose progress to nationhood is posing problems for the mother nation: the Falkland Islands off the coast of Argentina; the enclave of Belize on the border of Guatemala; and the Caribbean island of Antigua.
The Albatross is Canada, whose imminent request to have its constitution "Patriated" from Westminster to Ottawa is threatening the embarrassing spectacle of British parliamentarians haggling over how a huge independent nation on the other side of the Atlantic should be governed.
For Margaret Thatcher's government and the Foreign Office under Lord Carrington, these remnants of an imperial heritage are unwelcome diversions at a time when britain faces huge problems of its own. But all four demand solutions.
Canada's Prime Minister Pierre Trudeau alerady has informed Britain that his government will soon request Westminster to pass a law ending the eccentric arrangement whereby only the British government can alter the Canadian constitution.
In theory, Mrs. Thatcher and Lord Carrington would love to grant Mr. Trudeau his wish and give Canada control of its own constitution. For a while they hoped that such a law could be passed virtually without debate. Now that seems unlikely.
More than half of Canada's 10 provinces are insisting that Mr. Trudeau's tactics are anathema to them. The provinces claim they have their own direct relationship with Westminster and that neither Mr. Trudeau nor any British government can simply terminate arrangements dating back well over a century.
Mrs. Thatcher fears that a voluble group of her own members of Parliament will see things the way the provinces see them. There is even talk of a group visit to London early next year by all or most of the provincial premiers to petition the British government to be heard in their own right.
Compared with this possibility, the difficulties posed by the Falklands, Belize, and Antigua may seem minor, but in their own ways they present the Thatcher government with some awkward options.
The government would like to end the colonial status of the Falklands (population 1,800) either by ceding them completely to Argentina or by making complicated legal arrangements that would protect the islanders against the dictatorial ways of the Argentine government.
The trouble is that the islanders regard themselves as British and want to remain under the Union Jack. After holding lengthy talks in the Falklands and Argentina, a Foreign Office minister tried to persuade the House of Commons that the time had come for a clearcut decision.
He got the fiercest of roastings from a Commons not disposed to support any solution that might threaten to cut across the islanders' wishes.
The case of Belize (population 150,000) is a little easier for Britain. Whitehall does not trust Guatemala, which has threatened in the past to grab the tiny dependency. Now, however, the Guatemalans have lsot virtually all international support for their demand to be allowed to take over Belize, and Lord Carrington believes it is safe to grant the territory independence.
But still there is a difficulty. Belize could never afford to defend itself against Guatemala, so Britain may yet find itself having to sign a treaty with Belize, agreeing to send in troops if the country's sovereignty were ever threatened. A constitutional conference in London next year will grapple with this problem.
The case of Antigua (population 75,000) is not so simply as it looks either. The territory has had internal self-rule for 13 years and seems ready to go it alone.
Unfortunately for the Antiguan government, howeveR, the neighboring island of Barbuda (population 1,200) also wants to go it alone and become a nation in its own right.
A conference already under way in London is looking for a means of convincing the Barbudans that they are too small for independence and that other ways can be found to satisfy their political and constitutional sensitivities.