32 million votes were cast in 1992, over 14m of them for the Tories. 26 million were cast in 2010, 10.7m for the Tories. The Tory vote has not so much 'switched' since 1992, but just stopped voting. I think they were/are 'Thatcher's C1s/C2s', in other words the skilled and semi-skilled working class who have done so badly under Labour and mass immigration.
Cameron, Osborne and their modernisation project coterie of friends have obviously blown it. They thought (honestly) that by embracing unconservative irrelevances - ring-fencing the
Thomas Pascoe in the Torygraph Blogs:
UKIP are the party of grammar schools, controlled immigration, Euroscepticism and the small state. These are the values of the Conservative party members, whose devotion mitigates the inadequacies of CCHQ. They are also the values of many Tory MPs.
In fact, the only people in the Conservative Party for who those values are an anachronism are already ministers.