Using the UK Independence Party, we examine the effects of sudden electoral success on an Anti-Political Establishment (APE) party. The pressures of aspiring to government necessitate organisational structures resembling those of mainstream parties, while this aspiration challenges APE parties because they differ not just in terms of their policy profiles, but also in their more ‘unorthodox’ organisational make-up, inextricably linked to their electoral appeal. Robert Kilroy-Silk wanted to emphasise office-seeking goals while most members wanted the party to remain true to its APE status and not sacrifice its populist nature. This inevitably resulted in internal party conflict.