Farage has pretty much set his stall out for the most right wing group of UK voters comprising the older right wing Tories plus those Labour voters who admired Thatcher and who never migrated back to Labour.Probably comprising 25-30% of the electorate.Cameron meanwhile has decided to slug it out for the centre ground.The reason for this is that it comprises about 60% of the electorate from the Blairites and those slightly to their left who didn't desert New Labour because they thought it might move back leftwards.The trouble is he needs a majority of these to support him to get elected in his own right,about two thirds of them in fact.So if Miliband can hold to 25%+ this won't work,especially after losing boundary changes.That leaves 10-15% on the hard left,disaffected Labour and beard and sandals Libs.Farage therefore is unlikely to make headway under first past the post but holds a perfect spoiling hand.