Out of curiosity - usually party candidates deeply reflect their party platform. Under what circumstances would you want to vote for a party but not their representative candidate?

The leadership of the Greens are/were most closely aligned with my values – certainly at the time when the Blairites were still heading up the Labour party. So I wanted to vote Green as the party.

My local Labour representative, however, is a pretty good person to have looking out for the area. He was born and raised in the estates opposite my house - to a working class immigrant family, no less. In his time representing the area he's done a lot of good and he has a lot of experience. For me, that's all good - but his party values of continued austerity and benefit cuts don't sit well with me.

You see my conundrum? :)

Heh, failure of imagination on my part. Thanks for the clarification :)

your conundrum is that you have a distinctly minority opinion, but you would like to influence the outcome "more than your share"? so, instead of advocating unequal income distribution, you favor unequal outcome?

Erm, no, not in the slightest – well, I think not in the slightest – I'm going to be totally honest, I don't really understand all of your comment.

But I don't want to influence the outcome "more than my share". I'd like everyone to have an equal share of influence. More than anything I'd like the political process to be one that everyone is engaged in and ultimately moves the country in a direction that is good for everyone.

Not necessarily. This is a bit of an issue now in Canada because with have 3 (or more) left-wing parties, and 1 right wing party

This has led to a lot of ABC (https://en.wikipedia.org/wiki/Anything_But_Conservative) voting.

Beyond strategic reasons mentioned elsewhere, the main ones are (a) local candidate of desired party is unqualified/unpopular/etc and (b) local candidate of less desired party is more qualified/more popular/etc. (Seeing as "popularity" is, for better or worse, a pretty important quality in a political candidate; this includes "I went to the same high school as candidate X, they seem like a good person.")

This happens easily in more-than-two party systems like Canada or the U.K. Since each party overlaps with another a bit on certain issues, and many voters only seem to feel strongly about a few issues, those voters are ideologically okay with more than one party. Even if they have a "favourite" party, they will consider the candidates of those other parties as well.