If the Conservative party wins the UK general election next May, the British prime minister David Cameron has already promised to hold a referendum on European Union membership by 2017. Then, for the second time in four decades, voters will choose either to stay or to leave the EU. And Mr Cameron's success in renegotiating the terms of Britain's EU membership will influence their decision. But before that happens, other hurdles must be cleared. The first, next month, is Scotland's referendum on independence. If the referendum is carried, an independent Scotland could well cost Mr Cameron his job, and the Conservative party the general election.

In Britain, as these two major constitutional issues await resolution, the medium-term political outlook remains one of continuing uncertainty. This uncertainty has unnerved some US banks based in London, prompted them to reassess their options, and to plan ahead. They have considered various scenarios in making their plans: one is where the impending euro zone banking union leaves Britain more isolated; another is where the UK quits the EU.

Both developments would have an adverse effect on the City of London, which accounts for about one tenth of the British economy. Foreign banks in London have warned that a withdrawal from Europe could result in some banks withdrawing from Britain. Now some Wall Street banks have already made preliminary, albeit precautionary, plans to relocate some London operations either to Ireland, or Frankfurt – should Britain leave the EU.

Ireland’s appeal to foreign direct investors is clear, and well established for a long time: a low corporate tax rate, euro zone membership, an English-speaking population, and a familiar legal system. A British vote to leave the EU would not be in Ireland’s overall best interest. Nevertheless, one consolation would be the potential gains realised from US banks relocating some of their activities to Ireland, something on which, as one banker noted: “Dublin is selling itself very hard at the moment”.