Thirty years ago, then taoiseach Garret FitzGerald rejected a proposal that the three Ulster counties in the Republic should join with the six in the North in the interests of peace.

Newly released State papers include a file on partition in which, in January 1985, the Department of the Taoiseach responds firmly to the idea contained in a letter from a writer in Ennis, Co Clare.

"The taoiseach appreciates your good intentions in putting forward the proposal that counties Cavan, Donegal and Monaghan should join with the other Ulster counties in a new political unit. He regrets, however, to have to tell you that this proposal is wholly unacceptable as far as the government are concerned."

The response continues that there could be no question of the State ceding territory in the manner suggested, and it was “beyond doubt” that the inhabitants of the three counties affected would not accept such a solution.

“You advance in support of your proposal the argument that the unionist position would be guaranteed, whether they were in government or opposition.

“While you are not specific on this point, I take it that the new unit comprising the nine counties of Ulster would be independent of Britain, in which case, no effect would be given to one of the central elements of unionism, namely the British link.

“While your proposal would add to the size of the nationalist electorate the fairly even balance between the two communities would, in fact, be likely to make for further instability.”