Extraordinary plans to redraw the Irish Border - which included handing over County Tyrone to the Republic - were seriously considered by British officials in the 1980s, according to previously classified state papers released on Friday.
The radical proposals - which reached the desk of Britain’s prime minister Margaret Thatcher - also suggested ceding West Belfast, Fermanagh and most of Derry city to the Republic.
A briefing paper prepared by officials at the Northern Ireland Office (NIO), based on a new partition plan put forward by an academic, suggested slicing Northern Ireland in half and cutting its population by 500,000.
It also mentioned establishing a “walled ghetto” in west Belfast.
However, officials later noted that while moving half-a-million people -- mostly Catholics -- might be acceptable for a totalitarian regime, human rights arguments would be an obstacle.
Other incentives, such as loyalty tests for benefits and large-scale internment “should drive out large numbers”, they speculated.
The plans, which also discussed compensating unionists in areas ceded to the Republic, were quickly rejected as unrealistic and impractical.
But the fact they reached the desk of the British prime minister shows that they were considered at the top level.
The proposals are contained in UK government files from 1984, released under the 30-year rule.
Officials revisited the border question in response to research by Paul Compton, an academic from Queen’s University Belfast.
His “most respected analysis” is discussed in a secret paper prepared by the Northern Ireland Office. A copy sent to Mrs Thatcher and included in one of the files is heavily underlined, suggesting that she considered it in detail.