If the Eurozone does collapse, or if there is just a second European credit crunch, then Britain will be relatively insulated. We will still suffer a lot, but less than the Eurozone itself. However, the EU has a useful mechanism for sharing the pain: labour migration, guaranteed by freedom of movement within Europe. Although it is low compared to the US, it has still been high enough over the past decade to make immigration a big political issue in Britain. The government has pledged to cut immigration to the tens of thousands. Good luck with that when Eurozone unemployment increases above its already high level. There will be increasing pressure to pull up the drawbridges.