FWIW betting odds were almost exactly 50:50 over who would be prime minister after the election right up until the BBC exit poll was announced.

I just read the Wikipedia article on Prediction Markets, and thought others might find it interesting.

Basically, people can be betting monopoly money or only pennies, and they will make significantly better predictions than if you just ask them to guess. Some will use tools like Applies Information Economics to make surprisingly accurate predictions, at least on average. Others will still just guess, but they'll have a calibrated probability assessment, or perhaps will just be playing the game for the sake of better calibrating their probability assessments.

At some point, I need to calibrate my probability assessments, and put all this LW theory into practice.

I was looking at paddypower (they take bets on the election) and while they were more accurate than the polls they were still underestimating the number of seats the tories were going to get by ~50 seats. I think the safest bet the day before was the tories in a coalition.