Did Cameron's refusal to come to an arrangement with UKIP cost the Conservative party a majority?

Conservative Home have a list of the 21 seats where the UKIP vote was more than the difference between the Conservative candidate losing the seat and winning it. Now not all the UKIP voters would have voted Conservative but I believe that a very high proportion would have. Conservative Home headline this piece 'Did UKIP cost the Tories a Commons majority?' but I believe the fault lies with David Cameron and the Conservatives. David Cameron preferred to push his liberal credentials in an attempt to seem fluffy and nice and take votes from centrist Labour and LibDem supporters and ignored the Euro-sceptics in his party, UKIP and in the Labour & LIBDem parties. A deal with UKIP over the calling of a referendum might have prevented UKIP standing against Conservative in many if not all seats and could have meant a small Conservative majority. Instead of which the Conservative party is looking to deo a deal with the most EU friendly of the main parties.

UKIP supporters must be angry, EU-sceptic Conservatives must be angry; I am definitely angry.