Dacc
Depends how you measure it.
We're 5th nominal GDP, 9th in PPP.
The point is that import far more than we export, resulting in a trade deficit. And 79% of our exports are services.
Not all our financial services are going to move no, but some.
Banks are shifting jobs out of London due to the uncertainty of passporting rights - which allow them to operate across the EU. Paris, Frankfurt and Luxembourg are options.
HSBC have said 1000 jobs are moving to Paris on Brexit. JP Morgan have tried to calm fears they're moving, but have confirmed there will be some relocation. Dimon originally said 4,000 jobs. Some now say 1000. Grapevine says JP Morgan have leased 5 buildings in Frankfurt and 4 in Madrid.
Industry estimates are between 40,000 - 70,000 jobs may relocate. But PwC up to 100,000 by 2020.