JP Morgan's threat to leave if UK quits EU may bolster support for Brexit

British voters do not have much affection for investment bankers - many will see vague threats to go elsewhere as arrogant

Here comes Wall Street, answering David Cameron's call for the voice of business to be "heard in Britain and across the whole continent". Jamie Dimon, the chairman and chief executive of JP Morgan, suggests his bank would quit the UK if Britain exits the European Union. "Britain's been a great home for financial companies and it's benefited London quite a bit. We'd like to stay there but if we can't, we can't," he said.

"Can we have that in writing?" some UK voters may respond. Overpaid investment bankers, especially Wall Street types, are not held in high general esteem in the UK. Vague threats to leave the country will be viewed in many quarters as arrogant and may well be counterproductive for the Remain camp.