'I'd vote for the Lib Dems again, on one condition: That they ditch the Tories'

Could Nick Clegg present his opponents with their "Portillo moment" in 2015? Few would normally place a bet on the ousting of an MP sitting on a 15,284 majority, but Mr Clegg's old constituency faces being scrapped and, if many of his former voters are like the long-time Liberal Democrat voter Catherine Annabel, his victory is far from secure. The 54-year-old university administrator says she wept when the Coalition was formed.

"Oh God, the Tories are back," she thought as Nick Clegg strode through the Downing Street rose garden with David Cameron in May 2010. Her children simply did not understand what all the fuss was about, but she had a warning for them: "You weren't alive during the Thatcher years; you've no idea what these guys are really like." After a pause, she adds: "But they're learning rapidly now..."

Any predictions about the Liberal Democrat leader's political demise needs a heavy caveat: there is Sheffield, and then there is Nick Clegg's constituency. Far from representing the post-industrial, urban North in the Cabinet, the Deputy Prime Minister's constituency is a slice of prosperous suburbia amidst the lush scenery of the Peak District. With more than one in 10 earning more than £60,000 a year, it is one of the wealthiest seats outside the South-east of England. Even as Thatcherism ravaged the city in the mid-1980s, Sheffield Hallam remained an isolated island of Conservatism. It was only in the 1997 landslide that demolished John Major's Tories that the Liberal Democrats stole the seat.

"The typical Hallam resident is middle class, comfortably off, university-educated, and I tick all those boxes," says Ms Annabel. She isn't really feeling the squeeze, but it's the impact of government policies on the rest of Sheffield that leads her to regret plumping for Mr Clegg. "It's about the other extreme, which is Tinsley or Brightside."

Indeed, while Hallam has one of the lowest rates of unemployment in Yorkshire, there are nearly four times as many out of work in Brightside, just a few miles to the north-west. "I feel Mr Clegg is horrifically compromised by the Coalition," she argues. "All the common ground I had with him is kind of lost, really."

At the height of public enthusiasm for all things Nick Clegg, it was even said that he was the most popular party leader since Winston Churchill. He now has a personal rating of around – 30, but, even after abandoning key Liberal Democrat pledges, Mr Clegg retains local admirers. "I'm still very much a fan of Nick Clegg," says Diana Walton, a 65-year-old. "They've got a tough job down there. I'd still vote for him again." Government policies have had little impact on her life, and her main fear was the sovereign debt crisis sweeping Europe. "I feel for the Greeks and the Spanish. We've got to trim ourselves."

But it will be much harder to win back voters who feel conned into catapulting a Tory Prime Minister into No 10. "I feel as though my vote effectively allowed the Conservatives to take control, which is the last thing that I wanted," says Alistair Duncan, a 53-year-old chartered surveyor. As far as he is concerned, the Tories exist "to enable the better half, the well-off parts of society, to get an unfair share". Unlike Catherine, he didn't shed tears over the Coalition: instead, he felt "sick to the stomach to see Mr Clegg chumming up to his new friends in Downing Street".

Tom Calden, a 25-year-old computer manager with a 10-month-old child, shares the same sense of being tricked into helping the Tories: "Nick Clegg can sugar-coat it however he wants, but it is a Conservative government primarily." He estimates his family has lost up to £2,000 because of government policies, not least the withdrawal of working tax credits for part-time workers. "I feel like I've indirectly voted Conservative, and I think Cameron looks after his own."

Others were more direct about their fury with their local MP. Tim Bree, a 49-year-old training to be a probation officer, said, "I think he's disgusting," he said, jabbing his finger. "He made idle promises to steelworkers in this city, and once he came into power, he welshed on them."

What could prove tricky for Mr Clegg are the voters who have long been at the core of Liberal Democrat support. Students were inspired by Mr Clegg's commitment to abolish tuition fees, including the thousands attending Sheffield's two universities. Such was their enthusiasm at the last election that polling stations were overwhelmed. "Cleggmania" was the first time many of these young people became excited by politics, and it is difficult to understate how disillusioned with the system some felt after Mr Clegg supported the trebling of tuition fees.

The sense of a generation without a future is pervasive among student constituents. Jonathan James Guy, a 20-year-old Sheffield student, voted Conservative at the last election. With tuition fees hiked and youth unemployment soaring, Jonathan feels "my entire generation has been let down by successive governments. Our whole generation feels like we've got no hope."

All may not be lost for Mr Clegg, however: Catherine is not alone in suggesting she could return to the Liberal Democrat fold if the party withdrew from the Coalition. A betting man would go for Mr Clegg retaining his seat, should he seek re-election. But with so many of his colleagues facing electoral oblivion, this may be little comfort to an embattled party that – this time two years ago – entertained real hopes of replacing Labour as the "progressive party".