Did UKIP cost the Conservatives their majority?

Back in April, I wrote that it it would be interesting to see how many votes independent and small party candidates draw, and whether Labour lose as many votes to the BNP as the Conservatives lose to UKIP.

Today, Daniel Hannan writes:

Yet again, a largely Euro-sceptic country has elected a largely pro-Brussels legislature. A senior UKIP friend has run the figures, and tells me that UKIP cost the Tories 17 seats. If so, UKIP has probably let the Lib Dems into office: with five Sinn Fein MPs refusing to take their seats, 323 Conservative MPs would have constituted a bare majority.

There are two obvious problems with taking the "17 seats" figure at face value. The first is the source, which is clearly biased. The second is the dynamic nature of campaigning. If the Conservatives had gone sufficiently to the right to attract UKIP voters, how many seats would they have lost to the Lib Dems?

On the other hand, we do not know how many of the 16 million eligible voters who stayed at home were traditional Tories repelled both by the UKIP brand and by Modern Conservative policies.

Personally, I struggle to see how it would have cost Cameron votes to honour the spirit of his "Cast Iron Guarantee", and offer a referendum on Europe. The fact that the Lisbon Treaty has already been ratified is irrelevant. The only referendum this country has ever had was retrospective: on the 5th of June 1975, we were asked

“Do you think that the United Kingdom should stay in the European Community (The Common Market)?”

I say 'we'. Like tens of millions of people in this country, I had not yet been born. Moreover, the current EU is a far cry from a "Common Market".

Even the Lib Dems have said that we should get an In/Out referendum on the EU the next time significant powers are handed over to Brussels. Would the voters really have punished Cameron for offering that same referendum unconditionally, within 1 year of a Conservative government coming to power?

It may be that with the terrible state of our economy, Cameron doesn't want the distraction of a referendum. This is understandable, and perhaps the loss of votes to UKIP was inevitable.

However, it is also true that EU membership significantly restricts our options for radically overhauling our national economy.

Perhaps the best course is for Cameron to unilaterally disregard those EU restrictions that get in the way of our recovery. Initially these can be portrayed as short-term, emergency measures. As the years pass, the economy recovers, pressure from Brussels mounts, the Euro implodes, and the public increasingly see the benefits of going it alone, we can finally have our long-overdue referendum.

However, if a debate about EU membership at this juncture would be a distraction we can't afford, the same applies to a debate over electoral reform.

As Hannan concludes,

Let’s start with a referendum on EU membership. If the Lib Dems want a plebiscite on the voting system, fine: referendums are always and everywhere a good thing, serving to remind politicians that they work for the rest of us. But it would be preposterous to hold a referendum on how we handle the few powers that Brussels has left us, without first holding a vote on whether EU law should have primacy in the United Kingdom.