From the TUC

Robin Hood Tax unlikely to force banks to “leave” London

12 May 2011, by in Economics

A new report by IPSOS-MORI for the City of London finds that the main reasons banks locate somewhere are proximity to clients and availability of skilled labour. The business environment is a third reason, and regulation and tax are one element of that, but even there, it is predictability that banks want, not a specific level or type of taxation. So the common concern thata  Robin Hood Tax in the UK would lead to banks deserting the City of London and taking jobs and tax revenue with them is a fallacy, as the Robin Hood Tax campaign and the Financial Times (rarely on the same side of an argument) have argued before.

The Executive Summary spells it out:

it is clear from this research that three main sets of factors are most commonly central to business decisions to locate in a given financial centre: proximity to clients, the business environment (and, at present, particularly the stability of regulation) and the availability of skilled talent locally