From the Economist:

The SNP vote was part of a widespread rejection of Westminster politics. The solution for that involves fixing Britain’s broken electoral system. The SNP won about 5% of the popular vote in Britain and more than 50 seats. The UK Independence Party won about 10% of the vote but seemed likely to end up with one or two seats. With the relationship between votes and MPs in the Commons now almost random, the first-past-the-post method of allocating seats has clearly failed.

The case for topping up this creaking system with proportional representation, something this newspaper has long supported, has now become overwhelming. Tory backbenchers will object, but Mr Cameron might get enough support from others to override them—and would transform British politics for the better. For a weak government, that would be an impressive achievement.

It would. But they won’t do it.