Leading article: Sir Menzies and the limits of soft power in politics

Sir Menzies Campbell could hardly complain of any lack of advice before he delivered his keynote speech to his party faithful yesterday. All week his ears must have been burning with almost infinite variations on two fundamental questions: what were the Liberal Democrats for, and, was he not, at 66, too old to lead them into an election.

It is to his credit that he used his speech to tackle these questions head on. His reward was a reception of uncommon warmth and a shortening of bookies' odds on his remaining party leader until the next election. On the age question, Sir Menzies made the only argument that could be made: that "with age comes experience and with experience comes judgement". As evidence, he cited his party's opposition to the Iraq war, for which he was a persuasive Commons spokesman. He was entirely justified in doing so.

Sir Menzies took a decent stab, too, at explaining what the Liberal Democrats are for. In the opening passage of his speech, where he asked "what kind of a country is it" where green taxes have fallen as carbon emissions have risen, where the richest pay a lower rate of tax than the people who clean their offices, where MPs of the two major parties try to exempt themselves from freedom of information, and where a commitment to join the US missile defence scheme is "sneaked out" on the last day of Parliament, he neatly summed up the indispensability of the Liberal Democrats as a political force.

The two major parties may have moved towards the centre; they may also have advanced green issues higher up their respective agendas – and in so doing stolen some Liberal Democrat clothes. But there is still a coherent role for a third party. On the environment, they were the first in the field by a long way, and remain ahead of the other parties in their green credentials. They are the only party to project a real sense of urgency about climate change. They are also the only party to sound a note of wholehearted conviction in favour of Britain's membership of the European Union. When Sir Menzies said, as he did yesterday, that he favoured a referendum on EU membership itself, and would personally lead a "Yes" campaign from the front, he was credible. Would that Tony Blair, and Gordon Brown, have embraced Europe as unreservedly.

Sir Menzies did what was required of him yesterday. So why was it that, by the time he had completed his slow progress from the podium, many of the earlier doubts about his leadership and his party still hung in the air? Carefully composed as his speech was, Sir Menzies delivered it without the rallying quality so essential for convincing leadership. The party, he said, would be ready for an election whenever it came, but little real hunger for the fight was in evidence. And there was much more that Sir Menzies could have made of the party's uniqueness, not least on civil liberties, immigration and tolerance, where the party's voice needs to be heard much more loudly than it often is.

Whether a change of leadership at this stage is the answer, however, is by no means certain. Nick Clegg's artless confirmation of his ambition this week set back his cause without helping his party. But the Liberal Democrats have a place in British politics – and they should have a clearer message. There is no need for them to be as squeezed as they are between Gordon Brown and David Cameron, although it will be easier for the party when these rival leaders are more clearly defined.

This conference has shown that Sir Menzies may be less of a liability to his party than many feared. What it has not determined, however, is whether – come an election – he could transform himself into an asset.