When Britain leaves the European Union on March 31, 2019, it will need a treaty to cover security and foreign policy cooperation between the two. This article explains why and what the treaty should cover.
Since the Congress of Vienna, even in its imperial heyday, the UK has needed treaties with the countries on the continent of Europe to define its relations, alliances and conduct. From Vienna, through the Entente Cordiale and the Treaty of Versailles to the post-war settlement, we have seen a gradual evolution of these treaties.
The Treaty of Rome and its successors represented the most sophisticated form to date in defining these relations. They represent a grand bargain between all the members of the EU, from which each member state secured the most important thing that it needed, and accepted a degree of compromise on the rest to allow a balanced outcome that everyone could live with.