Clegg has yet to convince the public of Lib Dem achievements

Although the political close season was unusually busy with the riots and Libya, Nick Clegg made sure he spent time with his party's grassroots in every region of Britain. He was not surprised to find lots of bruises after its disastrous double defeat in May in the local elections and referendum on the voting system.

When they were stuck in perpetual opposition, the Liberal Democrats got used to being the nice party. So the activists who pound the pavements find it hard doors are slammed in their face. "We've gone from being a brand like John Lewis that no one dislikes to a Marmite party which a lot of people hate," quipped one insider.

Despite the wounds, the Deputy Prime Minister found on his tour that his party's members are a pretty resilient bunch. When I interviewed him yesterday, he described their mood as "surprisingly good given the pummelling we have taken ... It has been a rollercoaster year for us. It would be bizarre in the extreme if everyone agreed."

A few months ago, Mr Clegg expected a rough ride at his party's annual conference in Birmingham which begins today. Although there will be skirmishes, there is an absence of war.

When Mr Clegg walked across the threshold of 10 Downing Street last year, with David Cameron slapping him on the back, there was no turning back. He knew that some of his party members, and quite a lot of left-leaning voters, would never join him on his journey. Yet, despite the growing pains, he has reason to believe that the Liberal Democrats are now growing up.

When he addresses the conference next Wednesday, Mr Clegg will make no apologies for entering the Coalition. He can point to progress made and lessons learnt since the dark days of May. He has delivered the "muscular liberalism" he promised then, notably winning significant changes to the Government's NHS reforms.

The mood inside the Coalition has changed. Differences between the Tories and Liberal Democrats are more openly acknowledged. Although there are still many behind-the-scenes battles we never hear about, Mr Clegg has been more open about trumpeting his "gains". There are controlled explosions and there are uncontrolled explosions. From the outside, it is not always easy to tell the difference. When Mr Clegg claimed he had stopped the Tories from allowing providers of free schools to make a profit, some Tory ministers were miffed. But the Liberal Democrats insist there was a prior agreement at the very top to disagree in public.

The Liberal Democrat leader now has a story to tell his party, but must also use the conference to address the public. People have tuned out of the Liberal Democrats. "We need to regain permission to be heard," one Clegg ally admitted. "We need people to give us the benefit of the doubt again."

Mr Clegg's task over the next five days is to explain what the Liberal Democrats bring to the table. His problem is that it's difficult for any party to get the credit when the economy is flatlining and the spending cuts are starting to hurt. There are real Liberal Democrat fears that they have put all their eggs in George Osborne's basket. If his strategy doesn't work, some Liberal Democrats wonder, might the voters punish the Liberal Democrats for going along with it, but still hold on to Tory nurse for fear of something worse?

There is still time, Mr Clegg believes, to win brownie points for displaying the economic credibility Labour lacks, combined with a strong commitment to fairness the Tories lack in some voters' eyes – "competence with a conscience". A key target for the Liberal Democrats will be "soft Conservatives".

The Liberal Democrats don't need to tack right like New Labour or left like Cameron's Conservatives. They can justifiably claim they provide in government what they always said on the tin: they are a centre party now anchoring the Coalition firmly in the centre ground. To exploit this potential gap in the market and avoid electoral disaster in 2015, the Liberal Democrats need to trumpet a longer list of government policies that would not have happened without them and a positive agenda for the future.

The good news for Mr Clegg is that most of his party's members accept that the compromises of coalition are better than the wilderness of opposition. Having steadied Liberal Democrat nerves, it is time to starting winning over the voters. That will prove much harder.