Referring to the unionists, one Protestant member of the Belfast delegation said that “partition would place power in the hands of those responsible for the pogroms”.

The issue which faced the two sides in that second half of 1921 was the status, and size, of this new Ireland. Clearly something more than the old Home Rule had to be offered to the resurgent nationalists. And what was to be done about the recalcitrant north-east, which so valued its British culture? The government, in fact, had partitioned Ireland into six counties and 26 counties by its Government of Ireland Act of 1920, giving both areas Home Rule, run by Belfast and Dublin respectively. Though rejected by the South, Home Rule was accepted, reluctantly, by the Unionists of the North, the more quick-witted of them realising that this provided them with an inbuilt majority in Northern Ireland.

The Irish delegation at 10 Downing St proved their realism by accepting this division of Ireland – for the time being. Had they not done so, negotiations could not have commenced: the north of Ireland would have returned to its openly belligerent mode of pre-1914. Division meant that Unionists in the South and nationalists in the North would have to be sacrificed, but pragmatism dictated this compromise. The British Prime Minister, David Lloyd George, encouraged this acceptance by implying that a subsequent boundary commission would shave off large amounts of this Northern Ireland and hand them to the South, leaving the North too small to operate as a viable unit and thus eventually open to unification with the South.

The Irish delegation also might have preferred not to spend too much time thinking about the awkward example of the Unionists in the north, since their very existence, coupled with the principle of self-determination, meant some modification to the nationalist Irish case. At all events, it is interesting that neither during the negotiations, nor the subsequent debate of the Treaty provisions in the Irish Parliament, did the subject of Northern Ireland preoccupy the participants.

Of more concern was the political condition of the new Ireland. The British were unlikely to offer full independence; and, moreover, they would demand some sort of participation within the Empire. Inevitably such would mean a denial of Republican status – the holy grail for which the men of 1916 had fought and died. Perhaps this was one reason why the Irish delegation was not led by the self-appointed President, Éamon de Valera, the only surviving commandant of the 1916 Rising. He left the sacrifice (and consequent loss of popularity) to the original founder of Sinn Féin, Arthur Griffith, who now headed the delegation along with Michael Collins, the hard man of the guerrilla movement and master of urban warfare.

Collins quickly demonstrated he was no mere terrorist by his sophisticated negotiating skills; before long he was the dominant man of the Irish side. Facing him was the full panoply of the British inner cabinet, which besides Lloyd George included Winston Churchill and Lord Birkenhead. It was Collins and Griffith who were to persuade their colleagues to accept the unavoidable compromise.