Shirley Williams: I believe in a year or two Charles will be back

McChamberlain, some of his opponents on Iraq called him

Charles Kennedy has made the right decision for his family, his party and himself. Any leader must command the support of his MPs and of his party members. One without the other puts the leader's position in peril. So if Charles had insisted on fighting a leadership election, he would have divided and damaged his party to no purpose.

Charles's tragedy is that a brilliant career has been undermined by alcoholism. He brought a welcome humanity to politics, breaking away from the stale confrontations of traditional Westminster behaviour. He showed courage and determination in the face of brutal and vindictive condemnation of his stand on the invasion of Iraq, a misjudgement that will overshadow Tony Blair's reputation. McChamberlain, some opponents called him. He never let the party forget its birthright, commitments to social justice, civil liberties and constructive membership of the European Union. I, for one, hope and believe he will confront and defeat his demon, and come back within a year or two to frontline politics.

Now Menzies Campbell, our respected and authoritative deputy leader, becomes our acting leader. His experience and integrity are exactly what we need. He with Simon Hughes, the much-loved president of the party, can restore confidence and Liberal Democrat prospects at the local elections in May.

The Liberal Democrats established their identity strongly over Iraq. We have not done so effectively in domestic policy. Yet, as Norman Baker, MP for Lewes, said on Any Questions? on Friday, our position on civil liberties, asylum and immigration, criminal justice, the environment, pensions and health have been consistent and uncompromising. Time and again, it is Liberal Democrats in both Houses of Parliament who defy or seek to change legislation that makes inroads on our fundamental liberties, from identity cards, and peaceful demonstration to long periods of detention without trial. It is Liberal Democrats who argue for more imaginative ways of dealing with non-violent offenders and troubled adolescents than locking them up. Long before Adair Turner reported on pensions, Liberal Democrats were arguing for what he recommended, a decent universal basic pension coupled with a gradual increase in retirement ages.

But we have to shout louder. We should express our anger at the shortage of affordable housing, the subtle retreat from non-selective schooling, the shoddy compromise on targets for reducing greenhouse gases and on fair trade for developing countries. Above all, we must restate our commitment to social justice, and our disgust at the rapidly widening inequalities in our society, where City traders collect bonuses 30 or 40 times the annual salary of a teacher or nurse. A fine communicator like David Cameron presents the Tories as the compassionate party; yet neither their manifesto for the last election, which he wrote, nor their record bears this out.

Competition, less regulation in both the public and private sectors and rejuvenated local government are all objectives of the "economic liberals" that all Liberal Democrats can share. Better public services, a renewed attack on poverty, a fairer distribution of the tax burden and an education system that confers equal status on vocational and practical skills as on academic achievement are objectives of the "social liberals". They can and should be complementary.

Liberal democracy is the radical alternative to the other two major parties. It should not compromise itself in a doomed effort to emulate the Conservative or Labour parties. As Charles Kennedy demonstrated, it does not need to do so.