Re: The OP, it isn't surprising. Even without all the surrounding issues, Farage is a popular politician on his own terms and has had no trouble getting elected as an MEP before (although he has had considerably more trouble getting into the UK parliament primarily because of how the UK electoral system works).
He seems (somehow) to have deftly disassociated himself from what UKIP is at the moment and is doing what he does best - riding the populist wave.
Of course, Farage and his party have always done well from the fact that before the referendum was announced it was pretty much only hardcore eurosceptics who cared about Euro elections. Whether or not that is still the case is obviously unknowable at this stage, but I do wonder if BP will have stiffer competition from Pro-European parties this time than UKIP did previously.