Leading article: This historic opportunity must not be missed

This election campaign has felt almost like a liberation. The prison walls – the stultifying, spirit-crushing assumptions of the long era of two-party politics – have crumbled. The surge in support for the Liberal Democrats has unlocked something precious: a feeling among the public that, for the first time in a generation, a radical overhaul of our political settlement could be possible.

That feeling – combined with the enduring uncertainty over the result of the election – is a tonic for our democracy. The public sense that their vote matters. When one considers that this campaign began against a backdrop of rampant cynicism and apathy, stirred up by MPs' abuse of their expenses, this transformation looks all the more remarkable. And welcome.

But while this is a moment of hope and freedom, it is also a moment of danger for the popular movement for change that has been set free in recent weeks. Nick Clegg's party has made an astonishing breakthrough. But though the mould of British politics is fractured, it is not yet broken. And the vested interest of the "old politics" could still preserve it. Despite the drama of recent weeks, there remains a considerable risk that Britain could wake up on Friday morning to discover we are in for four or five more years of "business as usual" politics under a Conservative government.