Nick Clegg: No apologies. No regrets. No shame - He has been hounded by nine-year-olds on the school run, but the Lib Dem leader tells Matt Chorley he's convinced he is in the right

Briefly hailed as more popular than Churchill, Nick Clegg may well now be the most hated man in Britain. Effigies burnt in the street, dog mess through his letterbox, bike rides abandoned over fears for his safety. "I never imagined it would be any different," he insists.

Liberal Democrat leader; Deputy Prime Minister; architect of a new politics; and Judas to millions of students. The one-time political outsider sits forward on a plush, cream Whitehall sofa in defiant mood; belligerent even. "Not a week goes by without a commentator saying 'next week the coalition will fall apart', and not a week or day goes by without us confounding those views."

There must surely be times, though, when he has had second thoughts, regrets. "No. None at all. I'm absolutely convinced that almost any other course of action would have been a disaster for the country."

While the Secretary of State for Business, Vince Cable, is dizzy with concentric U-turns on whether or not he will back his own higher education policy, Mr Clegg is adamant he wants to vote for it - and urges colleagues to follow him, despite signing the now infamous pledge to "vote against any increase in fees".

He says he is still determined to tackle social disadvantage and educational underperformance, and says that a £150m national scholarship scheme will give a year's free tuition to 18,000 students on free school meals. Universities wanting to breach the £6,000 cap on fees, to charge up to £9,000, will have to give another free year to the poorest students.

In the coming weeks, months and years he will need to "grit my teeth, display a bit of resilience, and explain calmly and logically over and over again why we are doing what we are doing". The question is whether anyone will hear over the noise of disaffected supporters who believe their beloved party has been sold down the river for the sake of ministerial cars and jet-setting summits.

Economic recovery is key. Couple it with public service and political reform, and Mr Clegg clings to the idea that even the doubters - of which there are many - will return to the Lib Dem fold. "If there's one thing I'm not going to apologise for as the leader of the Liberal Democrats in government after 60 or 70 years of being out of government, it's that you just cannot avoid but deal with the world the way it is."

He is fresh(ish) back from Kazakhstan, representing the UK at a summit of the Organisation for Security and Co-operation in Europe. After a sleepless flight and 14 hours of meetings he returned home to look after his three children - his "wonderful and adorable" wife Miriam away on a business trip to the United States. One of his children "decided to puke in the middle of the night".

"The good thing is we are staying in our own house, we haven't moved into the Whitehall fortress," he says. But life has changed. Even the school run is not easy. A nine-year-old boy took the opportunity to present a petition opposing cuts to school sports.

He says a "cottage industry" has grown up predicting death for the Lib Dems on a weekly basis, but Mr Clegg, 43, has developed the supreme confidence of a Lord Mandelson, whose former grand office he now occupies.

He complains repeatedly that despite "punching above our weight in the coalition" the Lib Dems are not getting "a hearing at all on the policy stuff". Having come third in the election and made major concessions to the Tories, he says he must be upfront about the difficult decisions as early as possible. "Don't try and run away from it. Don't try to hide it, don't try and paper over it."

The coalition agreement pinpointed many of the "bumps, glitches and dilemmas" that lay ahead, including giving Lib Dem MPs the option to abstain on a tuition fees vote "if the response of the Government to Lord Browne's report [on university funding] is one that Liberal Democrats cannot accept".

Mr Cable, who drew up the response, said in mid-week that he may abstain, then said he would vote for it, then that nothing was decided. There are more arms to be twisted when MPs return to Westminster tomorrow. "Of course I would like everyone to vote for this; we are not there yet."

Thursday's vote will be the biggest test of his party in the coalition to date. "It is self-evidently extraordinarily controversial for us given the totemic status of our higher education policy." Vote against and it will fuel Tory suspicions that the Lib Dems do not have the stomach for power. Abstain and appear weak-willed and indecisive. Vote in favour and confirm the allegation of being an unprincipled sell-out to millions angered at the broken pledge.

"The allegation is made with the heart: it's 'you betrayed me'. And the answer is made with the head. When you have that, the heart always wins."

He is anxious to point out that both Labour and Conservatives were "wedded" to a tuition fees rise before the election and students would have faced an increase whoever won.

But he admits the deep anger felt towards the Lib Dems, the "passion, the hurt feelings, the demos and the slogans and the vitriol", risk deterring those from poorer backgrounds from going to university. "It's immensely frustrating to me to see a policy which lowers barriers of entry to university being portrayed as putting up barriers."

The National Union of Students, and its president Aaron Porter, stand accused of "not being straight" with the protesters who seem to think they are calling for free tuition when in fact they back a graduate tax - the policy also favoured by Ed Miliband. Mr Clegg asked officials to draw up plans for a graduate tax, but no version was "more workable or fairer" than the coalition's plan.

He does not expect ministerial resignations, although at least two members of the Government have warned they would quit if forced to back the increase. "We are no good in coalition government if rancour and bitterness and division creeps into our ranks." With the Lib Dem president, Tim Farron, comparing tuition fees to the poll tax and Mr Cable temporarily suggesting mass abstention, many in the Lib Dem ranks are unsure what their leaders want, and what is best for the country, the coalition and their own electoral prospects. Backbenchers in particular are frustrated at the apparent inability of the party machine to sell their policy "wins".

So Mr Clegg launches into a detailed explanation of what is planned to make university funding fairer. Upfront fees for the 40 per cent of students who are part-time have been scrapped and the repayment threshold raised. "If you were a care worker starting on £21,000 you pay about £7 a month. Under the current scheme you pay £81 a month and under the 2 per cent graduate tax proposed by Ed Miliband it's about £36."

"I believe in this policy. I really think we will look back in 10 or 15 years' time and think, actually that was quite a brave and bold and socially progressive thing to do.

"It's now time for the NUS and Ed Miliband and others to just come clean about what their proposals are, and then in an open contest compare it to what we are doing." He believes much of the anger now aimed at his Lib Dem bunker comes from Westminster greybeards confronted with something politically new, people who "don't like the fact that their comfort blanket of old pendulum politics has been snatched away from them".

Indeed sharing power is having a "transformative effect" on both parties. "I really do think it is quite a liberal government and has got a very strong liberal flavour." Right-wing Tory traditionalists take note.

His poll ratings may have nose-dived since the giddy heights of Cleggmania, though he argues: "Actually by some estimates we lost more in terms of the opinion poll vote share after the 2005 general election than we did after this one." He is adamant that in the long run the gamble of coalition will lead to an increase in vote share - and with it a long-term presence in government.

"I predict that with a bit of luck, with a bit of steel, with a bit of resilience, with a kind of discipline, we won't just recover but we will, I hope, reap the credit."

In his own words

On the tuition fees vote 'I'd like everyone to vote for this. We're no good in coalition if rancour, bitterness, division creep into our ranks'

On talks with MPs 'If you disagree, you disagree with everyone agreeing that everyone has had a chance to have a look at it'

On ministerial resignations 'I don't want anyone to leave. Sincere disagreement is the lifeblood of a strong party'

On class 'You know, I'm middle... I'm from an affluent background'

On student protests 'I was a student once as well. It's great going on demos and really having a crack at the government of the day'

On England's failed World Cup bid 'I just feel really heartbroken for the whole team that worked so hard on it'

On the old-Tory views of Lord Young and Howard Flight 'To say I disagreed with them is to put it very mildly'

On relations with David Cameron 'I don't think what the country wants is for us to become best mates. It's about, can we sort stuff together?'

On Lib Dems at the last election 'It would be lovely to wave a magic wand and live in a world in which we won the general election'

On Lib Dems at the next election 'We will be able to stand not only on a record but what we want for the future'

On being Britain's most hated man 'Is that an empirical assertion?'