There is a straightforward case to support AV derived from traditional conservative principles. Not to reflect the shift from main Parties since the 50s risks destabilising and de legitimising government. That is decidedly not what any Conservative would want so whats the problem?
The problem is, in a sense, the Liberal Party. Here you have a coherent organisation capable, in short time ,of leaping to the left of Labour and then allying with the right. It is a ruthless acquirer of power and seems capable of accommodating almost any point of view. Who , after all , in the modern UK is not as Liberal ? I am not criticising Clegg`s cloggers here, I am suggesting that the historical accident of its position in the UK is a block to proportional voting systems .
Whilst the principle of a greater proportionality may have some claim the fact of handing power in perpetuity to the Party the country likes least is obviously a perverse outcome .Furthermore the assumption must be that any shift towards proportionality must be the slippery slope a Liberal hegemony .
It is often said that elections depend on only 800,000 or so marginal seat voters . This is a fatuous observation , any majoritrian depends on a few voters the question the rest of us decide is which few . If the centre was a scattering of shifting alliances,a hot spot of fine gradations ,then non Liberals would not be disenfranchised .All the time this mighty toad squats on the centre however , the majority on each side are likely to suggest the current system is only unfair if you come third . The trick is to come second rather than change the rules .
Having said that, we are where we are and I personally cannot see that change can be avoided. Nor do I relish the prospect of another appalling administration of the Brown sort based on only 8,000,000 votes . The coalition , one senses, is at least in a position to govern at a time when the country needs strong leadership .
So its a bit of pickle really ,I look forward to listening to the arguments on both sides but I do not see it as an issue where the Conservative position is automatically agin'. The answer , ultimately ,is , I suspect the fracturing of the Liberal Party..