Perhaps expectations got out of hand? Perhaps we forgot that Cameron needed a bigger swing to win a majority than Margaret Thatcher achieved in 1979? Perhaps we forgot the hostility of the broadcast media? Perhaps we forgot the inbuilt bias in the electoral system that meant the Tories needed a much bigger lead in the popular vote than Labour to win a majority? Compared to Tony Blair's relatively smooth ride into Downing Street we shouldn't forget that Cameron had to cope with three massive events on his journey; a change of Prime Minister; the credit crash; and, of course, expenses-gate.
But although the mountain was tough to climb the party came angonisingly close to the summit. If the Conservatives had won 16,000 more votes across 19 seats David Cameron would be Prime Minister, leading a majority government. This General Election Review argues that a good campaign should easily have secured those 16,000 votes, and many more.