I think it might be helpful if you define how you are using the term conspiracy. Maybe you could give a few examples of some government conspiracies from recent times - say the last 30-40 years - that had no conceivable public good associated with them.

Canada, like the UK, has a multi-party system and the "losers" always complain that the winner didn't enjoy the support of the majority of voters therefore has no mandate. Like you, we have three mainstream parties (liberal, conservative and socialist) plus a bunch of fringe parties including the communists. But, like you, we also have a parliamentary democracy wherein the House of Commons debates government policy and the Senate (House of Lords there) provides "sober second thought". I don't share your view that this system spawns conspiracy just because the elected government represents less than 50% of the voters. In fact, it is far easier to be a conspiracist government when there is no effective oppostion. Gaining more than 50% of the popular vote typically means having over 80% of the seats in the House in a multi-party system. It is those governments that are far more likely to be arrogant, aloof and secretive.

I think the dynamics of governing in a democracy are somewhat more complex than you imply. The reality is that elected representatives, despite being members of a single party, have a variety of views on various issues. I find the whole process of building and maintaining party concensus fascinating.