Dr. Kieran McQuinn:

There was a landmark ruling some years ago when the European Central Bank took a case against the City of London arguing that trading houses in London should not be able to deal in euro-denominated bonds because the UK was not a member of the euro area. I believe the case went to the European Court of Justice, ECJ. Ironically, given how the ECJ is perceived in the British media, it found in favour of London and stated that, as long as the UK was part of the EU, it could continue to deal and trade in these products. That gives rise to the question of what the outcome will be if the UK leaves the EU and the case is brought again. If the outcome is that trading houses are not able to deal, it will affect a substantial proportion of financial sector activity in the City of London. The implications of that moving elsewhere will be huge.