Hero to zero: The dizzy rise and dramatic fall of Nick Clegg

Chorley I agree with Nick. All right, not on everything. Not on the wearing of yellow ties or that "Waka Waka" is Shakira's best song. But with some trepidation I am prepared to say that on the whole he was right to join the coalition, extracted a good deal, given the Tories only needed the support of 16 of his MPs to hold a majority in the Commons, and it is better that the Lib Dems are in government with the Conservatives than not. On Friday it will be exactly one year since the first TV leader's debate blew things wide open, Clegg became more popular than Churchill and halted Cameron's seemingly unstoppable march to power. Twelve months on, he has – apparently – become the most hated man in Britain and a "punchbag", to use the phrase of the moment. Is it all perfect? No. Has Clegg won every battle? Of course not. But is it better he is there? Absolutely.

Rentoul I'm no expert on Shakira, but I think Nick Clegg has got nothing out of being in coalition that David Cameron didn't want to do anyway – apart from a referendum on the voting system that he is going to lose. And even if he won it, it would be a miserable, self-serving gain, and I say that as a strong supporter of the Alternative Vote. But if that were all Clegg had to show for being in coalition, it would look bad because it just happens to benefit his own party.

Chorley We were told [by Cameron] that coalition governments wouldn't work – Clegg has proved they can. We were told electoral reform was pie-in-the-sky Lib Dem wonkery, but the people will vote next month. We were told the Tories would give an inheritance tax break to millionaires – Clegg blocked it, along with the marriage tax break. Instead he got a commitment that by the next election no one would pay tax on their first £10,000 of earnings, and is already half-way there.

Proof of the influence the Lib Dems are having is etched on the faces of Eurosceptics like Bill Cash and right-wing Tories like Norman Tebbit. Trident kicked into the long grass and the scrapping of the Human Rights Act shelved. Some draconian cuts to housing benefit delayed or ditched. Even on giving prisoners votes – with which I struggle to agree – there is no doubt that Clegg is having an impact.

Rentoul All the policy gains claimed by the Liberal Democrats are illusory. George Osborne was grateful for the excuse to drop the inheritance tax cut and to postpone the tax break for marriage.

The pupil premium is mere accountancy, and the civil liberties policies – mostly minor stuff at the margins – had already been adopted by the Tories when David Davis was shadow Home Secretary. As for votes for criminals, that was the European Court of Human Rights, not the Lib Dem Court of High Moral Sanctimony.

Chorley The people who bought the stuff about the Lib Dems being purer than pure were always going to be disappointed. But there were plenty who agreed with their policies who didn't vote for them because – with the history of demanding rights for goldfish and subsidised cannabis in school dinners – they didn't look like a credible party of government. At this stage, four years from a general election, it is impossible to tell what difference that will make to their re-electability.

Rentoul I think we can have a pretty good idea. As you say, one of the components of Lib Dem support was on the basis that they were not a party of power and therefore had some principles. Since they have been in government they have conformed to the Great British public's prejudice that all politicians will sell out their principles. So much so that "Why did Nick Clegg cross the road?" and "There are two things I dislike about Nick Clegg" have become staples of national humour ("Because he said he wouldn't" and "His face").

And, while the coalition sellout will exact a high price at the next election, Clegg has been used brilliantly by Cameron, entirely to the Tory party's benefit. Clegg the crumple zone absorbed most of the energy of opposition to tripling tuition fees. He has been a useful lightning conductor for the Prime Minister, and the coalition has been a valuable second stage of the strategy to detoxify the Conservative brand. Cameron emerges as the leader of a kinder, more liberal, one-nation Tory party, stripped of its Eurosceptic right wing, an electoral liability, without having to change any important policies. And the Lib Dems face electoral meltdown with no policy gains to show for it.

Chorley The opinion polls are not good, oh all right they're terrible, but I'm convinced that a silent majority are quietly happy that Clegg and chums are in government. However, they are drowned out by a vocal (and occasionally violent) minority of mostly students, rightly cross about tuition fees, and a huge herd of life-long Labourites who feel betrayed by the fact that ignoring and ridiculing the Lib Dems for decades somehow didn't secure a coalition of the left. A year ago no one knew who Nick Clegg was, even if he marched up to you in Newton Abbot high street and started bleating on about breaking the cosy consensus of two-party politics while you were on the way to Pound World. Now he is Deputy Prime Minister – an achievement not to be overlooked.

Rentoul The only thing that Clegg has got out of the coalition is ministerial office for him and 20 of his colleagues. Another self-serving benefit. And I do not believe that coalition itself leads to better government: that might possibly have been the case if Liberal Democrat policies had been robust and worked-out, but they weren't.

Chorley Only last week we saw the Health Secretary, Andrew Lansley, forced to grovel and "pause" his chaotic NHS reforms as an almost direct result of the Lib Dem vote at their conference in Sheffield last month and an – admittedly late – realisation by Team Clegg that all was not well with the policy.

Rentoul Andrew Lansley managed to mess that up all by himself, and would have had to be rescued by the Prime Minister whether or not the Lib Dems were around to exploit his embarrassment so opportunistically. Raising the income-tax threshold is the only policy that can definitely be attributed to the Lib Dems, and it's an inefficient way to make the tax system fairer. Raising the threshold benefits higher-rate taxpayers more than the rest, which means that other taxes on the rich have to go up to compensate. Surprising though it may seem, if he had been left to himself, George Osborne would have made the system fairer, with fewer disincentive effects at the upper end.

Chorley You're only cross because he said Tony Blair's Iraq war was "illegal" – an example of some consistency from Clegg since entering government.

Rentoul More than can be said for his position on the deficit. I agree with Nick (that his pre-election stance was the wrong one) but people voted for the Lib Dems on the basis that Clegg actually agreed with Alistair Darling that the deficit should be cut more slowly.

Chorley The problem was that, before the election, the Lib Dems were split between the professional managers who though they were preparing for government and the perpetual-opposition campaigners who thought they could say what they liked and never be tested. The two approaches collided most spectacularly when Clegg posed signing a tuition fees pledge he had already mentally dropped. The Lib Dem stance on the deficit shifted because ultimately they were the junior partner and the economic judgement is the big issue. What do you suggest they did instead? Not enter government, commit to the dustbin of history the idea that coalition politics could work, and risk another general election in October 2010 when the Tories would secure a majority?

Rentoul To prove that coalition government can work, they would have to gain some policy compromise rather than mere office and party advantage. If they had shifted Osborne a millimetre on the deficit, they might have been able to use the money to soften the blow of the tuition-fees sell-out. Given that they achieved neither of those things, it would have been better – from the point of view of those who voted Lib Dem – for them to let Cameron form a minority government and to fight each issue in the House of Commons. Then there might have been a compromise on deficit reduction and on tuition fees.

Chorley Under Ashdown, Kennedy and Campbell the Lib Dems were largely irrelevant and the butt of political jokes – about an affair, drinking and being too old respectively. Clegg turned the party round, repeatedly made the case for plural politics and is now in government – something no one expected 12 months ago when he first appeared on the TV debates promising "the way things are is not the way things have to be". He has been rightly maligned for the student fees U-turn, but the same betrayal didn't stop your mate Tony being re-elected twice. Maybe you think Ed Miliband would be better?

Rentoul The embarrassing thing is that I agree with most of the Government's policies, but they are Conservative policies, and the Lib Dems are still irrelevant and the butt of political jokes. If I were you I would put on the headphones, shut out the real world and have a good cry listening to Shakira.