You obviously didn't read my post of a few days ago which briefly outlined potential job losses on day one when we leave the EU or my posts regarding overtures made by the banking and finance industries to the Irish Finance minister immediately after the referendum.

The Government, no matter which colour, cannot prevent companies moving operations elsewhere.
I've found and read the link now: Brexity, City of London from the Guardian.
It is talking about a reduction of 10,500 jobs, but states that this figure has fallen from 12,500 a year ago. So it's just another estimate, possible more reliable than its previous one, possibly not.

The Government can't prevent companies moving elsewhere, it can only encourage businesses to remain, or move here.
there may even be a compensating movement of business to the UK once we are outside the regulation of the EU.

No one said that leaving the EU would be all gains, with no losses. many of those who voted to leave did so in the knowledge that there would be gains and losses, but looking at the overall picture.