Investors in the UK might not all get the chance to see the Brexit beer mats their Pub Chain Wetherspoons will roll out ahead of this month's referendum.

But not to worry, markets have entered June with enough referendum charter to leave even the most sober trader feeling light-headed.

Leading the way is the world's largest asset manager BlackRock, which declared itself wary of the sort of short term risk that Brexit poses to stocks.

That was followed by a gloomy warning of economic shocks from the OECD and a surprise poll that put 'leave' votes ahead.

Financial markets had virtually given up on the idea of a 'leave' vote in May,

resulting in a rally in the pound and in tighter spreads across peripheral sovereign bonds

as investors abandon the idea of a split reverberating across other discontented European regions.

Now, investment houses are starting sad, a little bit less sure of themselves.

The Chief Executive of Hermes Investment Management told investors on Wednesday that they would be wise to brace themselves for Brexit.

Currency traders are already taking heed and reacted to the latest poll by sending Sterling down sharply to a 2 week low against the dollar.

UK government bonds experienced a rally, sending yield on benchmark 10 year debt to a 2 week low of 1.37%.

Investors without the resources or the inclination to commission private exit polls in the manner of hedge funds

might be inclined to lighten their position in so-called risk assets at this point.

But for those who do not believe the UK will vote to leave the European Union, the narrowing polls offer an opportunity.

If the UK does vote to stay, an uncertainty in the lead up could lead to a post-Brexit bounce,

that could lift Sterling, raise equity prices, and tighten bond spreads in countries such as Italy, Portugal, and Spain.

This is the sort of easy calculation that can even fit on the back of a beer mat.