$4 trillion a day changes hands on the foreign exchange market, and half of that is in London. England is going to be OK, people. Project Fear has been voted down, after all.
I'm simply suggesting that may not be the case since EU is now likely incentivized to disrupt the current status if only to set an example. Rather than disrupt physical trade that is linked to export oriented mainland jobs, financial sector may be a riper target as barriers to moving these jobs are low (essentially no capital investment), disrupting it can be used to create jobs on the mainland and can create a punitive effect on UK.
That said, whilst it may seem tempting to run to the EU, other countries have been wanting to kill off the city and take its profits for their own for a long time. In the event of a remain vote, they may simply have been emboldened to outvote the UK and do it anyway, hence the focus in Cameron's negotiations on protecting the City. He knows it is vulnerable.
The banks now face a choice. Which is more risky/expensive. Needing to go through separate EU regulatory processes and get an EU "passport" via a subsidiary. Or relocate to e.g. Paris, and have all their activity be regulated by an EU now dominated by socialist governments rather than just some of it.
If this had happened 10 years ago they would probably have moved them to Ireland but that won't happen now.
This isn't scaremongering. It's just the way the banks have to do business. It doesn't directly mean that all finance jobs will move to the continent. They won't. But there will be a slow migration over the next few years.
It is also highly likely that, over the next few years, the EU will implement the finance reforms that the UK has been blocking e.g. the transaction tax. It is almost unthinkable that they won't implement that for UK banks.
It is also wholly in the EU's interest to delay a trade deal on services and financial services in particular as the UK has a significant surplus wrt the rest of the EU. It's more questionable over manufacturing as we run a deficit. How quickly we can negotiate a deal will be a toss up between industry that will want one and politicians who are likely to cause a fair degree of pain pour encourager les autres.
To me it looks like Dublin has lots of things in it's favour, not least the likelihood of an open border with the UK and native English speakers.
Because some have been there and it almost took out the Irish economy. They, the Irish, won't allow that to happen again any time soon. The fact is that the Irish economy is quite small and banks' balance sheets are quite big.
Realistically, only Germany, France and maybe Italy would be big enough to take a significant chunk of the UK banking sector.