The quoted Canadian study does not in fact make this claim. It does not even say that the Tory party has a near monopoly on the stupid vote. What it does say is that people with low intelligence are more likely to adopt conservative beliefs, which is hardly earth-shattering.
The study looks at the correlation of low cognitive ability and social manifestations, such as racism and homophobia, defined as prejudice against out-groups (feel free to substitute gypsies or catholics). In a nutshell:
Thus, individuals with lower cognitive ability may be more attracted to right-wing ideologies that promote coherence and order, and because such ideologies emphasize the maintenance of the status quo, they may foster greater out-group prejudice.The article also includes this amusing little explanation: "Crucially, people's educational level is not what determines whether they are racist or not. Social status also appears to play no part."
In fact, what the study said was that its analysis was controlled for education and socioeconomic status. In other words, they neutralised these as influential factors in the data, in order to better gauge the impact of cognitive ability. They weren't saying that these aren't factors at all. Education tends to reduce prejudice through the simple mechanism of social contact, i.e. once you've met a few "out-groupers" during freshers' week you tend to have less suspicion of them. Until they nick your sausages.
To cap it all, the article states: "The authors also claim that conservative politics is part of a complex relationship that leads people to become prejudices" [sic]. Your eye may have been caught by the closing typo, but the real meat in this air sandwich is the suggestion that prejudice may be the result of a complex relationship rather than just formal membership of the Young Conservatives.
This is an almost textbook example of shoddy journalism, or perhaps (if you prefer conspiracy to cock-up) a brilliant windup. The outraged comments on the Daily Mail site are a joy to behold.
For the footballistically inclined, here's another windup, this time targeting Spurs fans. According to a study I have just invented, most of them read the Daily Mail.