Sir, – Ending England's rule in Ireland (often shortened to "England Get Out of Ireland") is a perfectly legitimate expression of historic Irish-American wishes for Ireland.
Not only that, but using "England" as distinct from Britain makes the point that Wales and Scotland can hardly be blamed for the mistreatment and later in 1920 for the partition of Ireland. Furthermore, there is no way the unionists can claim that such a formulation implies they should get out of Ireland – no more than pro-UK people would have to leave Scotland when Scotland opts for independence.