The Conservative government of Edward Heath ordered a secret search among Britain's overseas dependencies for a remote island where any sudden influx of immigrants could be settled.
The Prime Minister began the hunt for an "island asylum" in 1972 after Britain was forced to accept 25,000 Ugandan Asians expelled by the notorious dictator General Idi Amin. Only the Falkland Islands showed any willingness to accept substantial numbers of new immigrants.
Ministers feared other East African nations such as Tanzania and Zambia might expel their Asian populations, who all held British passports. Mr Heath had fought a bitter battle with Tory right-wingers led by Enoch Powell over the decision to admit the Ugandan Asians and he feared that another mass wave of immigrants would damage race relations, which were already precarious.
The Cabinet acknowledged that in "extreme circumstances" it might have "no alternative to forcing a one-clause Bill through Parliament" denying UK passport holders the right to abode.
Ministers were concerned that MPs on the Tory left who had supported Mr Heath in his struggle with Powell and who genuinely believed in a multi-racial Britain would be "outraged" by such a move.
But they were forced to proceed with changes to the nationality and citizenship rules when the response to the search for an island haven drew so little enthusiasm.
Amin's expulsion of Uganda's Asians had caught the government by surprise. "We always thought that Amin was a decent chap," one official said. "After all, he served in the British Army for 15 years."
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