As the parliamentary expenses scandal continues to career between the baroque and the banal, the politicians at its epicentre are becoming ever more prodigal in their calls for constitutional reform. While some of this is half-baked, diversionary or a frightened reaction to the revulsion of the public, a real debate is getting under way about the relationship between power and the people in the UK. About time, too.

For this scandal has not only exposed the (mostly petty) venality of (many of) the honourable members of the House of Commons, it is also turning into a merciless X-ray of their role and functions: what exactly are MPs for and how does power work in this dysfunctional democracy? Restoring public faith in politics depends on getting the answers to these questions right.