All those who live or have at some point in their lives lived in a democratic society knows pretty much the spiel on voting: if you're old enough and are a citizen, you have the choice - when the time comes - to go to the booth and chose a candidate (or in some countries like Brazil it is legally required to vote). This is a very simplistic system, and not yet truly democratic. Why? because its rather restraining, and one is always presented with the scenario of "chose the lesser evil" as opposed to "chose your actual preference".
The Brits are trying to make some progress: the introduction of a ranking system for the contending MPs, where one instead of choosing one over the other, gives a list of preference in descending order. This they call Alternative Voting or AV. And of course there is considerable resistance to introducing this change. Please refer to your search engine for more information on this topic.
My criticism is that AV does not differ fundamentally from the earlier system. Sure it probably a better statistical tool to chose between alternatives, but in the end, the voters are still faced with the scenario of electing the lesser evil. And this is by all means a limitation. One can easily imagine how voting apathy is at the very least encouraged by such a limitation.
Here's a proposed change in the voting system. The ability to say "NO!". Perhaps none of the candidates are good enough. In mathematical terms this would be a negative point. Even in the AV system, one should be able to rank some MP negatively, expressing how deep their disapproval for that certain potential representative is.