There was a debate on the Guardian Comment Is Free pages today about the rights and wrongs of compulsory voting. Would it ever be a good idea? Absolutely, as long as, as many people on the Guardian Comment pages clearly said , "NONE OF THE ABOVE" is a viable option and tabulated accordingly.
In the UK's case, if NONE OF THE ABOVE were to win in a given constituency, that constituency would be considered to have effectively voted No Confidence in the candidates; if the number of NONE OF THE ABOVEs returned in the entire country were in the majority, then the population of the country would have voted No Confidence in all of the parties on offer.
In the first case, we have a local crisis, in the second, a national, constitutional crisis. Effectively, the population tells the government: you are not doing a good enough job - go away and come back with something better.
The UK is in dire need of this. After a number of chaotic elections, who knows - we may even come up with something democratic. Which is why of course no party in their right mind in the UK will ever let it happen. Let people decide what's going on? Heaven forbid!