In Scotland, you might think that Labour could do so by tacking further to the Left. But it doesn't matter how far they tack to the Left in Scotland because they will never be able to match the SNP's magic offer - nationalism. So the battle will have to be fought in the rest of Britain. And there Mr Corbyn will have to show that he feels the way existing voters do in key areas like defence, and the deficit, and immigration and, oh, hang on a minute…