There is an easy sense of lack of responsibility about reflecting on how you would cast your vote in an election in which you have no franchise. I never renewed my membership of the Labour Party after Tony Blair became leader, and since then at successive election I have floated around the left. But if I were a member of the Labour Party, I would vote for Corbyn.
That's not because I think he would necessarily make a great prime minister, but because he actually seems to have some ideological commitment which could get the Labour Party to think about what it actually stands for, rather than think about the various ways to chase the middle ground. To put it another way, he might represent a change from the 'how do we adjust our policies to attract voters?' approach to a more 'how do we convince people to follow us?' line of attack.
And, despite the anti-hype, he has the guts to say that people like me should pay higher taxes -- which, uncomfortable as it might be at the margins (and only at the margins, to be honest), must be right. Anyway, how this country got so hooked on the idea that low income tax was a good thing, when reducing income tax is only achieved by raising a load of other taxes, beats me.