I don't think the voting blocks are political - they're cultural.

A song that gets played on the radio in Britain is likely to get a lot of airplay in Ireland, and the Irish vote will go to the familiar British artist. If someone's on Europa Plus in Moscow every hour, chances are the stations in Ukraine and Latvia and so on will also play them.

It's not down to "we really hate Britain, so let's all gang up and not vote for them," it's down to "we're familiar with the people who are celebrities in our own region of Europe." The Eurosceptic British media would like us to think the rest of Europe dislikes us, hence the "political voting," "let's just leave Eurovision" narrative that comes out in the press every May.