This article aims to generate new insights into the City’s influence during the Brexit negotiations. Integrating theories of discursive institutionalism and business power, we set out to analyse the dynamic ‘discursive power’ of finance. From this perspective, a key source of the City’s influence historically has been a powerful strategic discourse about London’s role as Europe’s leading global financial centre. This was strengthened following the financial crisis to emphasise its contribution to the ‘real’ economy and emerging regulatory threats from the EU. We argue that Brexit challenges the City’s discursive power by removing ‘ideational constraints’ on acceptable policy discourse, and undermining the ‘discursive co-production’ of financial power by government and industry. By encouraging financial actors to re-evaluate their interests, this has contributed to increasing discursive fragmentation and incoherence. Evidence for this comes from the City’s ambiguous policy preferences on Brexit, and the emergence of a rival pro-Brexit ‘discursive coalition’.