Whilst I know they won't win I think each time I do this they get closer, and that takes us closer to some electoral reform, and some balance in a system currently dominated by the fights between two parties.
At the moment I doubt very much that picking my local MP on what he says will really make much difference, my dealings with my past two local MPs have been ineffectual, and more and more the Whips seem to have control.
If my vote can at least make other people think the next time that LibDem are getting stronger and more popular, and that there is a contest which is not just two parties, then it's worthwhile.
Having three parties who all have a chance of winning would hopefully make the parties consider what they do, rather than just opposing each other. It would hopefully bring some balance, and if the Lib Dems get there way it might encourage some electoral reform that brings power back to the people.
If the parliament is hung, so be it; Our politicians will start to have the power to decide, because the parties won't be able to control it.