Switzerland is not part of the EU. Think they are doing a-okay...
Well there is one major difference: the Swiss still meet most of the EU regulations and this has grown over time. If the UK leaves the EU they will go back to square one.... Every single treaty rule and regulation will have to be renegotiated and this will take years... In the mean time this will mean that a lot of companies will leave the UK pronto!
As London is not England I think that Boris made a BIG error as London has the most to loose... On the up side I can probably afford a house in London after the Brexit