Book excerpt: This book discusses how tensions and unknowns may impact future relations between a post-Brexit UK, the EU and the countries of the Gulf, including Iran. The authors of this book consider, in different ways, whether British and EU27 relations with the Gulf States may change or whether the traditions and the weight of their history reinforce the pre-existing patterns of these relationships. Ongoing changes in the Gulf, the present disputes and the trajectories economic reform also influence these discussions. The book analyses the changing positions of the US, China and Russia that are likely to impact Europe’s interests. It explores outcomes of ongoing world challenges, such as the COVID-19 pandemic and the crash of oil prices, to further examine Post-Brexit Europe and UK policy challenges towards Iran and the GCC States.