I think LibDem came close to overtaking the Labour party in the early 1980s! (But the Tories were way ahead of both).
As long as we have FPTP voting then minority parties don't stand much of a chance. Proportional Representation is the most common form of voting across the world which favours smaller parties, allowing coalitions to form.
Our local labour candidate is utterly useless so I'll be voting tactfully. I'm afraid I'm not a labour fan since Blair got my vote over scrapping tuition fees then reneged on it! I actually feel quite lost on who to vote for.