The dissertation examines the impact and importance of the EU’s Cross-Border Merger Directive as a tool for facilitating the use of cross-border mergers in the EU. It compares this to the position of cross-border mergers between companies in the EU and third countries such as those in the UK, by comparing the framework for the procedure and law governing intra-EU Cross-border mergers and the position of UK law on cross-border mergers post Brexit. By conducting a hypothetical and fictitious comparative analysis of two case studies involving a German and Irish capital company on the one hand and UK limited company and German capital company in GmbH form on the other, the dissertation highlights that Brexit removed from the scope of UK companies the chance to engage in potentially useful cross-border mergers, reducing the scope of creditor, shareholder and employee protection otherwise afforded by the EU law here.