A notable effect of ‘Brexit’ is that it will create new freedoms for the UK to shape its competition policy outside the EU, but these freedoms may come at a cost and could prove damaging to competitive markets. In merger control, the UK will be free to employ more frequent public interest interventions (especially for foreign acquisitions), but these could be misused and create uncertainty. In State aid, there will be pressure for greater protection of UK industries through State interventions, but such freedom will be constrained by the UK’s new trade arrangements and could prove wasteful. In antitrust, the UK will be free to set its own path, for example by fully criminalising its cartel enforcement regime, but cooperation with other EU competition agencies will dwindle and the UK faces difficulties in continuing to benefit from the significant level of fines currently imposed by the European Commission on its behalf. The paper concludes that any immediate changes to policy should be avoided and that it may even be necessary to legislate to limit the exercise of new freedoms. We also note how, at current EU/UK levels of enforcement, the Competition and Markets Authority’s resource requirement may have to be doubled.