So, the people responsible for the co-ordinated, nationwide subversion of the National Party's signage have been exposed after one of them gave a radio interview [audio]. Which just goes to show where ego gets you. Surely he knows that when you're doing something dubious, with a high chance of political blowback (say, by forcing the leader of the party you are affiliated with to apologise to your victims), you do not talk about it? What a dumbarse.
(As for the merits: while on one level billboard vandalism is to be expected, and sometimes appreciated by this innocent bystander when its amusing, a co-ordinated nationwide attack is downright dangerous. Elections should be about winning over public opinion, not thuggery. But this precedent invites the thugs to do the same, and that is something the rest of us can only lose from).