What is the explanation for the utter disdain of the Left for electable Conservatives?
Many people, who think themselves "progressive" (or on the Left) on most matters, do become quite emotional and hostile at the prospect of the Conservatives doing well.
(There is that usual comment from the "progressive", when attempting to be fair, that they have no problems with the "nice, old-style" Tories. This means that they like those Tories which lose elections.)
It seems not to be a matter of simple policy. The Blair-Clinton years saw "progressive" politicans adopt policies the Conservatives would have blanched at a decade earlier.
A policy adopted by a "progressive" government can usually be stomached without prompting real disdain in the Left. For example, the abolition of the 10p tax band, which has triggered concern in many genuine socialists, just looks hapless. However, it would have caused scream-ridden riots had it been done by the Conservatives.
Similarly, there are a number of us on the Right-of-centre (in my case, just) who strongly endorse particular "progressive" policies. For example, I strongly support full secularisation and a split between church and state, and evermore substantial movement towards social equality, especially in respect of sexual orientation and race. (I happen also to see the merits of free markets in economic growth and that the state is invariably inefficient, regardless of the expectations made of it.)
Nor is the disdain a matter of personality or even social background. Blair is quite as posh as Cameron or Boris, and he is indeed posher than every other Tory leader since Douglas-Home (who was an Earl).
(More generally, one must note that the Labour Party does seem to be led by either electable and affable Oxford graduates (Attlee, Gaitskell, Wilson, Blair) or chippy machine-politicans who rise up internally and then proceed to lose badly the first genuine election they ever face (Callaghan and, er, Brown).)
The disdain for electable Conservatives is deeper than policy or personality or social background, and clearly has an ethical base.
The existence of an electable Conservative Party is somehow a fundamental challenge to the moral order of the "progressive" mindset. Such a challenge thereby warrants outrage, insult, and incomprehension. It is a reaction comparable to that of a Medieval Christian learning of some popular heresy.
I suspect a typical Conservative is never outraged by people voting for the Left; disappointed, but not outraged. Support for the Left does not undermine the Conservative worldview, but the contrary seems not true.
Nonetheless, I do think there is a great deal of this disdain to come. And it will be "super-charged" by the growing realisation of the "progressives" that the Blair-Brown years saw the only real chance for at least a generation to have the majorities and the capacity to force through radical political and social change, but that hardly anything was actually done.
And, for the Left, the contrast here with the exploits of the Thatcher years will be extremely painful...