I don't think it's a case of political voting (except in the case of Greece for Cyprus and vs Turkey) the repeated failures of Norway show that even the Scandinavian/Baltic bloc can spot a lemon and are not that sentimental about voting for others if they're better. It looks like sour grapes when the Brits complain of everyone ganging up on them British entries have been really, really dire for a good few years. So have Ireland's imo though Lipstick wasn't too bad.
I think the issue is that the British song of late has been handcrafted by people who think they have the pulse of the European audience but are sadly deluded, and the ideal they have of 'appealing act' (apart from poor old Engelbert doing his patriotic best) is someone who could easily be either selling phones as a day job or somewhere in middle management in the cardboard box industry. Britain needs a competition where the input of more people's taste can decide who goes to Eurovision. There's no mysterious formula that can be cracked -- you just have to pick a song and act that appeals to people who are interested in voting and have phones. It can be tweaked afterwards.
(Norway needs to avoid smooth jazz, and ballet, and red trews, and of course purple anything)