Negative.
Their purpose seems to be to make the Conservative Party look reasonable. They claim to believe in "freedom and democracy", and yet they have a Lord as their Leader! He was also elected Leader with less than 50% of the vote.
No PM has gotten 50% of the vote for their party since 1931, so the vote share argument isn't particularly valid in a British context.
No PM has gotten more than 0. something of the vote for their party
ever.
My point was that UKIP claim to believe in democracy, and yet they use the undemocratic British electoral system in their leadership elections.