UK to leave European Union?

The common assumption is that when politicians invoke the name of Hitler they are losing the argument. Perhaps that's one reason why the betting markets point so strongly towards the United Kingdom voting to stay in the European Union.
And there must be other less apparent ones to explain why the Betfair price about staying in Europe is $1.42 with leaving being $3.30 for the opinion polls have things much closer as this poll-of-polls chart from The Economist shows:

Despite weeks of near level pegging in the polls, the market at Betfair on a vote to stay in has hardly changed.

Today's London Sunday Telegraph Hitler reference notwithstanding, that doesn't seem right to me and I hope my investing $50 on a leaving vote is not just because I am looking forward to Boris Johnson throwing the Conservatives into chaos by challenging for the Prime Ministership after a successful crusade for the UK to once again be the saviour of Europe.