Click here to watch Clegg's arrival in Edinburgh yesterday.

Click here to watch interview with Clegg.

The adrenalin was still running through Nick Clegg's veins when he returned to his private office in the Commons following his debut as Liberal Democrat leader at a raucous Prime Minister's Questions.

Staff broke out in applause, there were smiles all round plus a hug and a kiss from his mother. His wife called to give her support. Mr Clegg, a former MEP, spoke in Spanish.

"Of course, I was nervous but I actually enjoy it. I enjoy the House of Commons. It's a rough old place but it's such a privilege to speak on behalf of my party and quiz the Prime Minister.

"On the issue I raised (energy price rises), he frankly has not given an adequate answer. This is a big issue for millions of households, it's not just a debating point."

Mr Clegg decided not to crack a joke or deliver a witticism but asked serious questions, which most observers felt he did rather well. He passed the first Westminster test: avoid the elephant trap and making a fool of yourself.

The son of a half-Russian father, Mr Clegg has cited his Dutch mother, Hermance van den Wall Bake, who was imprisoned in Jakarta by the Japanese during the Second World War, as the biggest influence on his politics. He speaks five European languages and is married to a Spaniard, Miriam Gonzalez Durantez, with whom he has two sons.

Asked what the point of the LibDems was, it took the party leader a few seconds to get his brain in gear. "To make Scotland and Britain a more liberal country," he finally declared.

The fresh-faced politician, looking a tad younger than his 41 years, spoke passionately about civil liberties; he has said he would to go to jail if ID cards are made compulsory.

"South of the border, we are seeing a top-down, heavy-handed, at times a fairly authoritarian approach to civil liberties, which is completely contrary to the instincts to all the British people."

Mr Clegg cannily praised the Scots for their more liberal attitude than the folk down in England.

"Let's take the moves in Holyrood to protect private information from any ID card scheme and the way in which the Scottish Executive has used DNA databases in a much more selective way than they have south of the border. You have a kind of liberalism in Scotland which we should learn from in the rest of the country." Praising your hosts is not a subtle move but always a welcome one.

Mr Clegg also touched on Scotland's more enlightened approach to asylum seekers, mentioning dawn raids and how this contentious issue had "enlisted more of a humanitarian response north of the border than south of the border".

Sensing some might think his approach wishy-washy, he stressed: "Of course, people should be sent back home if they are here on a false claim but there is also a strong liberal, humanitarian sense in Britain - which runs very deep in Scotland - we also have to treat these people like human beings."

The day after he became leader, Mr Clegg received a phone call from Gordon Brown, offering to work with him on constitutional issues.

But, amid the conviviality, the LibDem chief made clear he was not interested in "playing games" but in a serious cross-party look at a whole range of matters from Lords reform to PR and how Holyrood works with Westminster.

"I, in effect, said to him he should either put up or shut up. I'm waiting for a response from Cameron and Brown to my specific proposal to set up a new all-party convention looking at political renewal in the United Kingdom along the model of the Scottish constitutional convention." He could be waiting a while.

As for Scotland and the cross-party move towards greater powers for Holyrood, Mr Clegg insisted the LibDems were in the driving seat, emphasising how at the elections last May his party was the only one to advocate greater powers for the Scottish Parliament. Times have changed.

He warned Mr Brown that it would be "extremely foolish" to close his mind on the subject and would simply offer a political gift to Alex Salmond and his followers.

Although pro-coalition, Mr Clegg made clear that the LibDems would not jump into bed politically with anyone. Their decision not to join the SNP administration was made "on principle": they did not believe in independence.

Stressing it was for Nicol Stephen, the party leader in Edinburgh, to decide on matters of coalition north of the border, Mr Clegg nonetheless observed: "Alex Salmond seems to me to be a politician who subjugates pretty well everything to that overarching aim of securing independence for Scotland, an aim with which we strongly disagree."

Mr Clegg's main mission is to get himself and his party noticed, seeking to make his party stand apart from the Tories and Labour by concentrating on issues like the environment, poverty and civil liberties. He appears to see only opportunities.

"It's terrifically exciting, but more than that I'm just optimistic. All the signs are that if you look around you particularly in the Westminster environment you've got two larger parties that are living in denial.

"They are living in denial because they are trying to sustain a two-party system that is dying on its feet.

"In the 1951 General Election, 97% of all people voted for Conservative or Labour Parties. At the last General Election in 2005 it dropped well below 60% for the first time; that is a precipitative.

"People are voting with their feet and are walking away from two-party politics. The opportunity for a strong, self-confident liberal voice which seeks to change the way we do politics and promote a lot of liberal values, which are dear to a lot of British people, certainly dear to a lot of Scottish people, suggest there is great potential for us to grow rapidly in the years ahead."

Mr Clegg's ambition is to at least double the number of LibDem MPs within two General Elections. It is a bold one but that, after all, is what ambitions should be.