Snub: Liz Kendall says she will refuse to work with Jeremy Corbyn if he wins race to succeed Miliband

Labour leadership hopeful Liz Kendall will refuse to work for ‘ridiculous’ Left-winger Jeremy Corbyn if he wins the race to succeed Ed Miliband. And she won’t give him a job if she wins – even if he comes second.

The snub by Kendall came amid growing fears that Corbyn – considered a no-hoper a month ago – could pull off a shock win. If he does, Kendall says Labour will become a laughing stock and be out of power for a quarter of a century.

Speaking to The Mail on Sunday at her Westminster office in the most outspoken and candid interview she has given during the leadership contest, Kendall:

Taunted rivals Andy Burnham and Yvette Cooper for refusing to back her vow to boycott Corbyn.

Said Labour could have won the General Election if David Miliband, not his brother Ed, had been leader.

Accused Ed Miliband of spending too much time focusing on the poor and not enough on the middle class.

Unmarried Kendall, 44, also spoke openly for the first time about her personal life.

She scoffed at cruel comments about being a ‘childless spinster’ and expressed ‘sadness’ at breaking up with comedian Greg Davies.

Mocked as ‘Tory Liz’ by Labour enemies, Kendall revealed she buys her clothes from two of Kate Middleton’s favourite high street stores.

When Kendall threw her hat in the ring after Labour’s Election defeat, the power-dressing Blairite was seen as a potential winner – with scruffy-bearded Corbyn regarded as sure to finish last. Now the roles are reversed. Corbyn is the front-runner with 55 nominations from local Labour parties, with Kendall last with just ten.

She says she can still win and a Corbyn victory would spell disaster for Labour. ‘People would think we were ridiculous if he was elected leader. Taking us to the hard Left and turning us into a party of protest means we will be unelectable and in the wilderness for a generation.

‘Some people think we can have everything we want without making any difficult decisions. They have forgotten what it takes to win. It is fantasy politics.’

She says she would not give Corbyn a job under any circumstances if she wins – nor work for him if he triumphs.

She claims Burnham and Cooper refuse to take a similarly tough stance. ‘They have been asked the same question but wouldn’t say no.’

Kendall fell out with Burnham when they worked together in Labour’s Health team.

The key to Kendall chic: With her habit of using the same shops as the Duchess of Cambridge the Liz look isn't cheap. The prices for her interview outfit are: LK Bennett shoes £195, Reiss jacket £225 (£95 in sale), Reiss trousers £120, Reiss v-neck tank top £30. Total £570 (£440 in sale)

And she was furious at jibes by Cooper’s allies that she was unfit to be leader because she is single and childless – unlike Cooper, married to Ed Balls, who has three children.

‘When people say, “You don’t have a family” it makes my blood boil. I thought, “Yes I do, I have my dad, my mum, my brothers and nieces”.’

Kendall never expected to be the Blairite torch-bearer. It was thrust into her elegant hand when Chuka Umunna stood down after protesting that the media attention was all too much.

Taking us to the hard Left and turning us into a party of protest means we will be unelectable and in the wilderness for a generation Labour leadership hopeful Liz Kendall

No-nonsense Kendall, born in Abbots Langley, near Watford, comes from precisely the kind of aspirational Middle England family successfully wooed by Tony Blair and foolishly spurned by Red Ed. Her mum was a primary school teacher, her Labour-supporting dad left school at 16, working his way up the ranks at the Bank of England. No prizes for guessing where his daughter gets her stringent views on Labour overspending from.

She was head girl at Watford Grammar and won a place at Cambridge, though she was persuaded to take it up only after her mother talked her out of pursuing her dream of becoming a professional dancer.

She captained the women’s football team at Queens’ College, Cambridge, while achieving a first-class degree. Her first job in Westminster was as an aide to arch-Blairite Health Secretary Patricia Hewitt, and Kendall remains New Labour to the tips of her stilettos.

She backs a role for the private sector in health, says Labour must focus on ‘creating wealth as well as spending it’, wants more money for the Armed Forces, backs welfare cuts, and has defended free schools.

Snub: Labour leadership hopeful Liz Kendall will refuse to work for ‘ridiculous’ Left-winger Jeremy Corbyn if he wins race to be next leader

Nor does she conceal her low regard for Ed Miliband. Was the he chiefly to blame for Labour’s defeat? Yes, says Kendall. Would the party have won under David? ‘He would have had a much better shot.’ She adds: ‘We said a lot about the very poor, but too little about the middle classes. We have to help both.’

Kendall is irked that the leadership contest has drawn attention to the fact that she is childless and has never married.

She was in a relationship with Davies, who played a teacher in The Inbetweeners, but it ended earlier this year. Who ended it? ‘I’m not going to tell you. It didn’t work out, sadly.’

Is she seeing anyone now? ‘No.’

Does she want to get married and have kids?

‘As you get older, of course you want to be settled, but life changes and it doesn’t work out. Who knows what will happen? That’s all I say. I am a person who loves and wants to be loved.’

Kendall maintains her lithe figure by jogging 20 miles a week. On Saturday nights she loves to dance to rap music at discos with friends. When I arrived for the interview she was still getting ready: ‘Hold on, just putting on some lippy.’ She is wearing emerald green suede high heels from L.K. Bennett. I ask how much they cost. ‘About £100 I think.’ The L.K. Bennett website says they are £195.

Her jacket, navy blue ‘vest’ and trousers are from Reiss. L.K. Bennett and Reiss are two of the Duchess of Cambridge’s favourite fashion brands – and slinky brunette Liz, or Elizabeth Louise, to give her full Royal-sounding Christian names, looks as good in them as slinky brunette Kate. In fact she looks the same weight as the Duchess – about 8st – though when I ask she slaps me down with a raucous ‘f*** off!’, adding quickly: ‘Don’t print that.’

Kendall says that if she is elected leader she would be ‘decisive with no fudge.’ But she denies claims by Labour foes that a Commons aide resigned after she hurled a stapler at his head in a rage.

‘God, no, I’ve never chucked anything at anybody!’

I show her an article by a female newspaper columnist which sneered: ‘Childless old spinsters like Liz Kendall end up leaving their cash to the donkey sanctuary.’