On 2 July 2017 the government of the United Kingdom announced its intention to withdraw from the 1964 London Fisheries Convention (LFC). Plans to reshape the UK’s fisheries policy, including a 2017 Fisheries Bill, had already featured in the Queen’s speech on 21 June 2017. The Common Fisheries Policy (CFP) of the European Union has been unpopular with the UK’s fishing industry – and has been widely perceived as one where the UK may have more to gain than to lose by leaving the EU. The UK’s announcement has triggered mixed reactions. Michel Barnier, the EU’s Brexit negotiator, tweeted that it made no difference for the negotiations. Not all EU Member States are, however, fond of the prospect that the UK might use reciprocal fisheries access as leverage in the Brexit negotiations or –in the worst case scenario– close its waters to foreign fishing. Denmark has reportedly built a case against the UK based on “historic fishing rights” dating back to the 1400s, which it claims it could bring before the International Court of Justice (ICJ) if negotiations fail. This post takes a closer look at the implications of the UK’s denunciation of the LFC for Brexit and the question of historic fishing rights.