Unlike many ‘modern’ nations, the UK was formed over several centuries through various unions, each of which retained traces of earlier epochs. First was the union between England and Wales during the 1530s, then two unions (regal and parliamentary) which created ‘Great Britain’ out of England and Scotland in 1603 and 1707. Finally, that ‘united kingdom’ of Great Britain joined with Ireland in 1801 to form the United Kingdom of Great Britain and Ireland, modified after 1922 to Northern Ireland, making the UK in its current form less than a century old.

Indeed, much of the terminology still familiar in the early twenty-first century is derived from the debate surrounding ‘Home Rule’ for Ireland in the late nineteenth and early twentieth centuries. ‘Nationalists’ supported Home Rule for Ireland, while ‘Unionists’ opposed it. The latter term entered the political lexicon when, in 1886, the Liberal Party split, with its anti-Home Rule wing calling itself ‘Liberal Unionists’. Yet this terminology, like a lot of political language, was reductive and masked important nuance.

Firstly, ‘Home Rule’ did not (initially) mean the formal secession of Ireland from the 1801 Union; rather it meant the ‘devolution’ of certain policy responsibilities to a new (or revived) legislature based in Dublin – not unlike the devolution later granted to Scotland and Wales. While Home Rulers recognised Ireland's claim to this devolution on nationalist grounds – i.e. Ireland's status as a distinct ‘nation’ – they sought to reform the UK rather than end it. Contemporary hyperbole also helped muddy the waters, for political and media opponents of Irish Home Rule often accused supporters of being ‘separatists’.

On the other hand, ‘Unionists’ neither denied Ireland's nationhood nor the desirability of separate administrative arrangements and ‘national’ institutions – as in Scotland – they simply regarded the creation of an Irish parliament to be unnecessary and potentially detrimental to both the UK and its empire (for a thorough discussion, see Jackson 2003). Following the partition of Ireland in the early 1920s, however, to be a ‘unionist’ came to mean one of two things: either someone who supported the preservation of Northern Ireland as part of the UK, or a believer in the continuing (and earlier) Anglo-Scottish union.