Two conflicting views of the UK constitution exist: a Whitehall view, which treats ministers as the centre of the system and a Westminster view in which the House of Commons is central. In the former, British democracy is defined by elections to choose a Prime Minister. In the latter, elections choose a Parliament to which governments are accountable. Under united majority governments, the conflict remains hidden, but it emerges under minority or divided governments. The Brexit crisis was such a period. Its defining constitutional disputes – how far governments can act without Parliamentary approval, whether governments could close Parliament or veto bills, whether the Commons was justified in seizing control of its agenda, whether governments should continue after losing control of the House and whether the Fixed-term Parliaments Act changed conventions about confidence – all reflected aspects of the conflict between the two views. The Westminster theory gathered support in the Supreme Court and Commons, but the ultimate dénouement, a general election bringing to power a majority government, vindicated the Whitehall view. The crisis casts doubt on the Whitehall view’s viability in periods of political change, but also on whether Westminster politicians can make the Westminster view work.