Immortalised by Kipling, ‘if’ is a very big word. As the UK general election approaches, it is increasingly punctuating the narrative of lawyers’ private conversations as they try to anticipate the potential consequences of ‘Brexit’ – universal shorthand for Britain’s possible exit from the European Union (EU).

Three big ‘ifs’ must be satisfied as preconditions for this ugly word to take effect: if Britain elects a new Conservative government with an outright majority; if the much-heralded in/out referendum occurs; and if a majority of voters then say ‘yes’ to EU withdrawal, leading to Britain’s unilateral exit.