Excerpt:
Margaret Thatcher was strongly opposed to admitting women to the UK who were the second wives of men in polygamous marriages, Cabinet Office files show.
The then prime minister also believed there was a danger of the government favouring "the coloured Commonwealth" at the expense of the UK if it did so.
The newly-released file covers immigration policy from 1982 to 1986.
The document shows the issue of admitting second wives created constant difficulties for Thatcher's government.