Civil servants in London prepared a "last ditch" plan in 1974, for possible use in the event of a full scale civil war which would see Roman Catholic inhabitants of the north east forcibly moved to Fermanagh, Southern Londonderry, Tyrone, South Armagh and South Down. Protestant inhabitants in those areas moved into North Down, Antrim, Northern Londonderry, and North Armagh. The nationalist areas would then have been ceded to the Republic of Ireland. An alternative plan simply involved "moving individual Catholics from their homes in Northern Ireland to new homes in the Republic". The plan was kept secret at the time and was revealed in 2002.
So what if, had the troubles moved to full scale civil war (which could have happened at quite a few different PoD), that this plan had been implimented?
Also, if instead, Wilson had done this, as part of the 'Doomsday' plan? http://news.bbc.co.uk/2/hi/uk_news/politics/7610750.stm
Thoughts? Either plan being implimented is certainly within the realms of possibility, though both equally bloody.