Blimey, great post.
Only one problem.
I agree completely that the real question is "Who are the right/best people to decide (when and) whether to go to war?"
You then say that Politicians clearly are not. They depend upon mass appeal for their jobs and always have their voters to consider. I agree again. Especially the current PM, for whom opinion polls and focus groups seem so important - 'Do the popular thing and then argue that it's right' not 'Do the right thing and then argue the case for it'.
But you then go on to argue that "the least worst choice and that, in our democracy, is the elected government."
Having rightly castigated politicians we're back with them, especially now that the executive has so little accountability, and treats parliament with such contempt. In some respects the "Back-benchers (especially ex-hereditary Peers) and those in marginal constituencies, Trade Union leaders (vote seekers again) and Church leaders" are surely more useful because they are less controllable by Mr Blair's whips, and more accountable to their constituents than to Party leaders.
The answer must be that our elected government is the right choice, but only as long as it pays some heed to the other groups you describe, whether it be the electorate ('the proletariat and the chattering classes!'), the media (who can only ever reflect different public opinions - don't credit us with power, please!), industrialists (some of whose interests are our interests), and academics. I think that the government should listen especially hard to military officers, for obvious reasons.