It would have been more of a surprise if the coalition had decided to hold its referendum on voting reform on a different day; for example in October.

The working assumption for the last month has been that the ballot would co-incide with the May 5 local elections, as the BBC is reporting this morning. The only arguments against that had been that a] it could confuse people if they had to vote on two separate things and b] the Electoral Commission may not be in favour. Neither seem to be major obstacles.

The Lib Dems are itching to get on and hold the referendum as soon as possible; for many it is the one major reason for being in government – as strange as that may seem to sceptics.

Their first challenge will be explaining the AV system to people and then convincing them to care one way or another. The second will be rebutting a strong anti campaign by their supposed friends in the Tory party.

Meanwhile Labour will not hesitate to exploit the situation to its own advantage. Forget the fact that some Labour figures have gone public on their enthusiasm for electoral reform in recent years. (Some have seemed more sincere than others). Key frontbenchers see the referendum as a golden opportunity to force the downfall of the coalition, as splits appear between the yellow and blue partners. Read more