Over the last few years I have come to know and, at different points, have collaborated together with both of the two main leadership contenders (as well as Steve Webb, who while I was writing this, seems to have withdrawn from the race!).

But the one I will be voting for is Nick Clegg.

I’ll be doing that because I believe he would bring to the leadership of our party many of the things which would give us the opportunity to break forward from the plateau that we have reached over the last few years, following rapid success through the 1990s.

Firstly, he obviously has undoubted skills in presenting what he and we believe, in a way which is not only liberal, but which comes across well to normal people, as well as paid-up Lib Dems. He is very much, as was often said about Charles Kennedy, a fully-signed up member of the human race - and he has a facility in talking about real life which I think comes across very well to people who are not very interested in politics. And of course anyone who has seen him speak at party conference or elsewhere will know how effective he is at presenting political ideas too. So I can’t see any other of our MPs who can come close to him in doing the crucial part of the Leader’s job which is presenting us coherently and appealingly to the outside world.

Nick is however not just a presentable mouthpiece, of no particular fixed ideological abode - or in other words, David Cameron. I don’t say this just to be abusive about Cameron - this seems to me to be, along with their political views, to be the crucial difference between Clegg and Cameron. You only have to talk to Nick in private for a few minutes to realise how engaged he is in the world of ideas - and not just the idea de jour of the political world, but in some of the key clashes of ideas in the big picture of where we are going as a country and in the world.

The approach he has taken in what now seems destined to be his short period as Liberal Democrat Shadow Home Secretary, is an interesting example of this. Bluntly, being Lib Dem home affairs spokesman has generally been seen as a challenging chalice to be given: the public think that the Lib Dems are soft on crime, and every new spokesman takes a look at Lib Dem ratings on crime issues, and tries to make their own attempt to do something about turning them around.

Many simply don’t make a lot of progress. Some of the boldest try and end up failing in a more spectacular fashion: the prominent recent example here is Mark Oaten, who promoted a range of measures under the slogan ”˜Tough Liberalism’ which alienated many in the party to such an extent that, to the surprise of everyone, he couldn’t even gain sufficient support among parliamentary colleagues to be a candidate in the 2006 leadership election.

A natural reaction by Oaten’s immediate successor might well have been to accept that there was not a lot that could easily be done by the Lib Dems to reverse perceptions of us on home affairs issues. But Nick Clegg has taken up the challenge, and one of his first major initiatives was the motion he brought to conference last month on immigration policy. Starting from the firm liberal ideological foundation that Nick has, this achieved a remarkable balance between (a) tackling the traditionally politically-radioactive issue of what can be done about the many hundreds of thousands of immigrants in the UK who, in one way or another have “irregular immigration status”, (b) limiting the number of new immigrants - and (c) traditional and deep-seated liberal instincts to accept and protect diversity and those who want to come and live in this country.

This was a tightrope walk which had the potential to have the right-wing press attacking him from the right, and many in the party attacking him from the left. But in fact although there was indeed some criticism in the press, he not only got the motion passed at conference on this highly sensitive issue, but he did so without any significant internal opposition to it, and without creating a firestorm in the press.

Being prepared to take on the difficult issues that are holding us back as a party, and successfully winning broad, if not unanimous, agreement to new solutions, is another thing that Liberal Democrats can scarcely afford to overlook in a potential leader.

Immigration is a home affairs example, but as leader, I believe Nick Clegg would help us to find solutions across the whole Liberal Democrat front. Indeed, this was something I was reminded about again at the remarkable and very slightly surreal fringe meeting hosted by the Independent at conference last month.

Messrs Clegg and Huhne, who had both been bending over backwards to avoid giving the impression of pre-fighting a leadership contest that at that time (despite what the press were saying) seemed still some way away, effectively found themselves tricked into a head-on debate with each other, when they arrived at the meeting to discover that the other members of the panel that they had been led to believe was addressing the meeting, did not in fact exist. It was a head-to-head presentation. And for those of us in the audience, the event offered us, despite the best efforts of the protagonists, a guilty opportunity to compare them.

Both of course spoke very well across a range of issues. But what really struck me was the manner in which they replied. Chris tended to give a strong, solid and clear response on the question asked, based in many cases on real knowledge of the issue that the questioner had asked about.

But Nick, on the other hand, answered the question but then also used it as a starting point to begin to explore some of the really big issues and political challenges that the question pointed the way to. Here was someone, one sensed, that instinctively wanted to take on some of the serious philosophical and political challenges and obstacles for the Liberal Democrats.

This surely has to be something we look for in a leader, and I hope we will install someone with those instincts in the driving seat of our party.

I don’t by the way want to disparage Chris Huhne. I have also had the opportunity and privilege to work with him. He obviously has immense professional success behind him - including building up a highly successful large City firm from nothing - as well as huge intellectual capacity which the party has done very well out of over many years (long before he was in either the Westminster Parliament or the European Parliament). It is for example in large part due to him that over the last 18 months we have gone from being a party with a strong commitment to green issues to being one with a highly impressive array of concrete policies for actually implementing that commitment. He also has instincts on many issues, such as localism, where I strongly agree with him.

And as a strong pro-European I cannot less pass without comment my satisfaction at seeing that both of the potential candidates for leader have a strong background belief in European means as part of the solution to the challenges which Britons face in our daily lives. This is good for Britain and it is also good for us as a party - since I think having an unashamedly pro-European leader potentially also allows us, based on that solid foundation, and on the “it took Nixon to go to China” principle, to do things differently on Europe than we sometimes have in the past.

But for the reasons I’ve set out, I do believe that Nick Clegg is the man for our party - I will be supporting him and I urge you to do so too. With this man I believe we could really go places.

I do however issue one warning to the party about Nick. Do not choose this new leader if you came into this party seeking an easy ride. Taking the party forward is all very well - I fully support it! - but you don’t achieve that without challenging the party’s voters and indeed its members. As I have said, I don’t doubt Nick’s liberal foundations and that what he does will be firmly grounded in them, but if we want to present ourselves differently, then part of that means, well, sometimes presenting ourselves and our ideas differently. For most of the last few years, the party has got used to not being challenged, and when it does happen, not everyone in the party always enjoys it.

As leader, Nick Clegg would challenge the party. The potential rewards in return for accepting that challenge are exciting, I believe. But if you are one of those who think the key job of the party leader is keeping all of the people happy all of the time, then I think you should think twice before voting for this candidate.

Personally, however, I am enormously excited about it. Under Leader Clegg, we could have some very interesting times ahead of us.