Chapter three measures the political influences of ‘new’ and ‘old’ Irish nationalisms in Britain from the aftermath of the 1916 Rising to the aftermath of the 1918 general election. It profiles the political languages and cultures of ‘Irish-Ireland’ nationalism in British centres: Gaelic League-Sinn Féin-I.S.D.L.; charts the decline of the Irish Parliamentary Party’s British political influence; and evaluates the impact of the 1918 Representation of the People Act on Irish political representation in Britain. While advanced Irish nationalist associations were central to the organisation of relief campaigns for interned rebels in British centres, the 1916 Rising, this chapter submits, did not fundamentally change Irish nationalist politics in Britain. Conflicted over Redmond’s earlier refusal to join the British Cabinet, the Irish Party was instead debilitated by the absence of political leadership, and a post-war political manifesto, in Britain. While the Irish Party in Ireland was decisively defeated by Sinn Féin at the 1918 general election, the Irish Party in Britain was effectively displaced by the Labour Party. The ‘victory’ of Sinn Féin in Britain was predicated less on the democratic legitimacy of Dáil Éireann and more on its recognisable post-war mandate: an Irish Self-Determination League.