International regulatory co-operation (IRC) provides an opportunity for countries to consider the impacts of their regulations beyond their borders, to expand the evidence for decision-making, to learn from the experience of their peers and to develop concerted approaches to challenges that transcend borders. This review documents the context of IRC policies and practices in the United Kingdom. It covers both the UK's unilateral efforts to embed international considerations in domestic rulemaking and its bilateral, regional and multilateral co-operative efforts on regulatory matters. In addition, the review provides a snapshot of IRC in practice in the United Kingdom with four case studies on financial services, nuclear energy, medical and healthcare products and product safety. At a time when IRC is an increasingly essential, yet largely untapped, tool for addressing transboundary policy challenges, this review offers valuable lessons to countries within the OECD and beyond.