UK Conservatives missed opportunity with UKIP

http://www.actoncampus.org.nz/blog/why-the-conservatives-really-lost

From ACT on Campus Blog:

In November 2009, UKIP offered to not contest the UK general election at all if the Conservative party promised, in writing, a referendum on the EU Lisbon Treaty. The Conservatives ignored the offer.

They go on to make the case that, had UKIP not contested the election, David Cameron would have had a majority. By my reasoning, the results would have been like this:

Party	Seats	Majority	Seats w/o UKIP contesting	Majority w/o UKIP contesting
Conservatives	307	16 short	330	Majority of 15
Labour	258	65 short	242	81 short
Liberal Democrats	57	with Conservatives: Majority of 83 with Labour: 8 short	50	with Labour: 31 short
DUP	8	with Conservatives: 8 short	8	with Conservatives: Majority of 31
Others not including Sinn Fein	15		15

note: Majorities calculated assuming Sinn Fein do not take their seats, and assuming the Conservatives will win the one remaining constituency, Thirsk and Malton, which is a safe Tory seat. The speaker is included in the conservative tally.

Bottom line: The Conservatives lost because they refused to promise a referendum on the Lisbon Treaty.

This was done assuming all UKIP votes would have gone to the Conservatives if UKIP had not contested, which is nearly fair judging by how similar their other policies are. To be fair, i will also show a table of what would have happened if only half of the UKIP vote is given to the Conservatives: (assuming the other half vote evenly, vote for other 3rd parties, or stay at home):

Party	Seats	Majority	Seats w/o UKIP contesting	Majority w/o UKIP contesting
Conservatives	307	16 short	321	2 short
Labour	258	65 short	248	75 short
Liberal Democrats	57	with Conservatives: Majority of 83 with Labour: 8 short	53	with Conservatives: Majority of 103 with Labour: 22 short
DUP	8	with Conservatives: 8 short	8	with Conservatives: Majority of 13
Others not including Sinn Fein	15		15

So even in this case, they passed up an opportunity for an easy coalition with the DUP and a referendum, for an almost unworkable coalition with a centre left party.