A not so funny thing is happening on the way to next May’s general election. As energy and conviction drains away from the major political conferences, some of it is flowing into Nigel Farage’s ragged insurgency. So serious has Ukip’s ambition become that platform speakers at its own conference have finally stopped boasting about how many pints they sank the previous evening.

Since the 2014 conference is being held this year in Ed Miliband’s backyard, on sun-soaked Doncaster racecourse, the development is doubly tragic: Ukip activists sober a few feet from where the world’s oldest classic horse race – the St Leger – was run just days ago. The St Leger is not a teetotal occasion. Yet at lunchtime on Friday bars normally heaving with punters looked as puritanical as a New Labour seminar.

Ukip’s leader, who has not personally signed the pledge, turned in the first of two promised Farage barnstormers in mid-afternoon on Friday, after a diffident debut (“thank you for so many kindnesses”) from Clacton’s Tory defector, Douglas Carswell, and a warm-up man who memorably observed “ I sometimes worry how Nigel can walk....” We all do. But after rock star’s welcome and a very long drum roll he duly appeared, sleek and radiant.

Not quite like Miliband in Manchester, Farage ad-libbed his speech, but did it better. He is a man of simple certainties, confident, funny (“On the deficit” – pause – “I nearly forgot the deficit”) and fluent, an English Alex Salmond marketing hope through panacea nationalism. He does it well. “We love Europe, we hate the EU” and “We’re not against immigration, but we think a British government should be able to control its quality and quantity.” He even told delegates to give Nick Clegg a vote of gratitude.

All day on TV sets in conference corners members of the hated “Westminster elite” joined David Cameron and Ed Miliband – Doncaster North’s “champagne socialist millionaire MP” is Ukip’s declared target here – in debating the bombing of Iraq. If it was an attempt to bomb the conference’s publicity (“it probably wasn’t,” admit delegates) Ukip isn’t bothered. Abroad is not a major party interest except as a source of low wage migrants, a threat to living standards of Ukip’s new target: Labour voters.

It is still Ukip, of course. Delegates (1,650 of them by midday) are mostly lower-to-middle class, middle-to-old-aged white people, hordes of elderly bald men with red faces and moustaches (a terrifying sight); kilts, straw boaters and striped blazers, women dressed elaborately in Ukip gold or purple, a few tattoos and eyebrow rings too, a smattering of posh and Paul Sykes, ex-Tory zillionaire developer and Nigel-backer. More black and Asian faces than before. Some nasty things are said, some daft ones, but fewer than before. The nutters and Brussels piss-artists are under lock and key.

“It’s grown a lot since I attended our conference in Scarborough in 2002 when Freddie Trueman was the guest speaker,” recalls Jim, a retired building worker from nearby Scunthorpe and 16-year Ukip veteran. “People used to tell me: ‘It’s a wasted vote, Jim.’ Now they say: ‘You were right.’” Sykes agrees. “You could have fitted this conference into a phone box 10 years ago. But the dam has broken, we’re going to steal the Labour heartlands now.”

How are they going to do that? Much as the SNP has been doing in Scotland, with a combination of disdain for Labour (“It’s betrayed the working class”) and the Tories (a privately educated, plundering Oxbridge “chumocracy”); that and nostalgia for a sepia-past when you could trust the NHS and not feel a stranger in your own street. Plus tentative steps to flesh out policies beyond the touchstone issues of Europe and immigration. Europe? Before Farage spoke it was barely referred to except as an ATM machine from which enough money can be repatriated to pay all the promised higher spending and lower taxes. So the theory goes.

Lots of it amounted to having other people’s cake and eating it.

A better deal for ex-soldiers and for NHS nurses (not managers), for children deprived of the grammar school ladder by the Oxbridge crowd, for hard-working immigrants who want to integrate but not for returning teenage jihadis (don’t let them back). Jane Collins MEP – most speakers were MEPs, the floor never got a word in – savaged the failure of Labour-dominated Rotherham to protect vulnerable girls from Pakistani and Kashmiri predators. It was brutal, alas mostly true.

But there were also cheers for multiethnic sentiments (and speakers), for inclusion and tolerance, albeit at a lower volume than for the red meat of Britain-first nationalism.

At the back of the racecourse’s packed conference hall Ukip’s veteran press officer, Gawain Towler, offered potted CVs of speakers. Collins is a miner’s daughter from Pontefract (dad walked from South Wales in the 1930s). Slick Steve Woolfe MEP, is a financial services lawyer, but Moss Side born to a Jamaican mum. Natasha Bolter, who bolted from Labour, is also of mixed race, an Oxbridge type (a first in PPE), who chose to come home and teach in East London.

Standing at the back listening to Farage, Warren Bates has tried them all. Fifty years with Labour, a union convenor, he feels “the party left me behind”. Bates tried the Greens and Lib Dems before settling on Ukip where he’s now an Oldham councillor. Completely the opposite are Lindsey and Stephen Musgrove from Surrey. They didn’t even vote until they saw Farage eviscerate Newsnight’s Emily Matlis in 2012 “and something snapped”. Stephen is now a Ukip councillor and Lindsey, a former legal PA, works for Collins. “We live in a political moment where the country has changed a lot in ways that touch on ordinary people’s lives,” he explains. Economic uncertainty and falling living standards touch Surrey as they do Doncaster, a once proud industrial town betrayed by politics, delegates were told on Friday.

The language deployed on Friday had a raw authenticity increasingly lacking in the measured soundbites of the established political class. Perhaps a new such class is being born, nationalist, free market and libertarian when not being just the opposite. For all the attacks on elites most of the whoops and cheers were from delegates notably less well dressed than the increasingly polished speakers – on stage and on a roll.

• This article was amended on 29 September 2014 to correct the spelling of the Yorkshire cricketer, Freddie Trueman.