Having run through the Conservatives (who want to shrink the state a little, just wont say how), Labour (who want to grow the state, and balance the budget, except the latter doesn't add up) and UKIP (who want to shrink the state a little more, except for healthcare, education and immigration), what about the others?
The Liberal Democrats are the other party of government, who have taken a schizophrenic approach over the years since the Liberal Party merged with the breakaway Social Democrat Party in the 1980s. It was in the centre, then when Blair led the overthrow of Saddam Hussein (and the green political religion was in ascendancy) it moved left. Now, it has spent five years supporting a Conservative government in coalition, and has been severely hammered by its voters, used to feeling morally superior by supporting policies that they knew would be highly unlikely to be tested with reality.
Given Labour's swing off to the left under Ed Miliband, the Liberal Democrats are playing the only logical card they have, by claiming to be more fiscally responsible than Labour, and more "caring" than the Conservatives. For a libertarian this doesn't mean a lot. The Liberal Democrats are happy to support some lower taxes, but also support new taxes on the "rich" including a mansion tax. Beyond that it is much of the same, except for a commitment to five new environmental laws, and the Liberal Democrats are solid supporters of retaining EU membership. What sliver of liberty remains is a belief in a slightly less criminalised approach to cannabis, solid opposition to further state surveillance powers on communications (which both Labour and the Conservatives battle to support), and a handful of candidates (such as Jeremy Browne) who are more "classical liberal").