One of the strange things about General Election campaigns is that you can never really predict what will capture the public imagination.
Day after day, the nation's politicians trudge up and down the country, and most people barely even notice they're there. And then, quite suddenly, a stray remark seizes the nation's attention and can never be wiped away.
Two years ago, for example, Theresa May travelled the land intoning her terrible mantra about strong and stable leadership, and nobody cared. Then she told an interviewer that the worst thing she'd ever done as a girl was to run through a field of wheat, and everybody remembered it.
For Boris Johnson, that moment came during his mock-spontaneous campaign video, released online a few days ago. In case you haven't seen it, the Prime Minister is interviewed wandering around his campaign headquarters, making a cup of tea and greeting random staff members.
He talks about wanting to get Brexit done, and about liking Marmite. Then comes the remark that, in the public mind at least, seems to sum him up.
What, asks the interviewer, has surprised him most about being Prime Minister?
The biggest shock, he says, is that he can no longer have a takeaway. The other day, he adds, 'I couldn't actually get a Thai curry to deliver to Number 10 because of the security problems'.
Classic Boris, you might think. The kind of man who's desperate to get stuck into a decent curry. A man who likes the Rolling Stones and forgets to take out his teabag before pouring in the milk. A man of the people.
Of course, there's more to it than that. You can bet that every line in that campaign video was carefully scripted, right down to the last syllable. As recent months have shown, Johnson is a very canny, even ruthless, operator and he knew exactly what message he was sending.
Indeed, his critics — some of them inside his own party — claim the whole thing is an act. They point to his upper middle-class background, his classical education at Eton and Oxford, his plummy accent, his membership of the Bullingdon Club, even his air of carefully manicured dishevelment, and see an Establishment figure in populist clothing.
But that takeaway line resonated because it matches what the public already think. For in Johnson, many working-class voters do see a man of the people, to an extent unmatched by any Tory leader in living memory.
The very fact that so many people automatically refer to him as 'Boris' is very telling. Even that campaign video begins with the interviewer, in a strong Estuary accent, greeting him with the words: 'Hi Boris, all right?'
Even when he went to South Yorkshire, meeting residents who were angry that the official response to the floods had not been quicker, people automatically called him by his first name. 'You've took your time, Boris, haven't you?' said one heckler.
Afterwards, the Mail's man in Yorkshire, Chris Brooke, noted that even diehard Labour supporters, who thought he should have done more to help the flood victims, invariably called him 'Boris', not 'Prime Minister'. And although they might not be his biggest fans, many were pleased to shake his hand and even sit down for a cup of tea.
Nobody called Mrs May 'Theresa'. Nobody bumping into her predecessors called David Cameron 'Dave' or Michael Howard 'Mike'.
The last Conservative leader to whom ordinary voters referred by her first name was Margaret Thatcher — 'Maggie'. And she was the last Tory leader who strongly appealed to ambitious working-class voters, not least because she sold them their council houses.
Yet according to the latest polling data, Johnson's appeal to working-class voters is even stronger than Mrs Thatcher's in the early 1980s.
A ComRes poll this week, for example, found that fully 43 per cent of skilled and semi-skilled manual workers — those people at the bottom of the social pyramid — are planning to vote Conservative, up from just 35 per cent in 2017.
A YouGov poll, meanwhile, found that among all working-class voters, the Tories are on 47 per cent, a staggering 20 per cent ahead of Jeremy Corbyn's Labour Party.
This picture might change on Election Day, of course, but I doubt it. Every last bit of evidence suggests that the Tories are far more popular than Labour among working-class voters, turning the time-honoured stereotypes of British politics on their head.
Not all of this, mind you, is down to Johnson. Contrary to Labour gibes that the Tories have never been anything more than the party of the rich, they have typically attracted between a quarter and a third of the working-class vote.
But in the past few years, there has been a marked surge in the Tories' working-class support. Some 38 per cent of working-class Britons voted Tory in 2017, the Party's strongest showing since 1979.
One of the central factors, obviously, is Brexit. Some political scientists believe Brexit has shattered the old political alignment, with millions of voters abandoning old haunts for new homes.
For the Conservatives, the obvious downside is their abandonment by affluent urban Remainers who might once have been regular Tory voters. In 2017, for example, they lost Canterbury, a classic leafy, middle-class university city, for the first time since 1835.
Or take Oxford West and Abingdon, which is positively stuffed with PhDs. The Tories won it in 2010 and 2015, but lost it two years ago to Lib Dem Layla Moran, almost entirely thanks to Brexit.
But the Tory calculation is that they can afford to lose seats like this if they pick up more working-class constituencies in the North and Midlands. They have high hopes, for example, of winning the veteran Dennis Skinner's seat in Bolsover, where as recently as 2005 they came third with just 17 per cent of the vote.
To capture Bolsover would be extraordinary indeed, but it is part of a pattern. The Tories' route to victory depends on success in the North, where they hope Labour voters' frustrations with the Brexit impasse, fury at the metropolitan political class and utter contempt for Jeremy Corbyn will outweigh decades of tribal loyalty.
This is where the Boris factor comes in. To paraphrase the old Heineken advert, Johnson refreshes the parts other Tory leaders cannot reach — in particular, the declining towns of Northern England.
Obviously Brexit, again, is part of the story, since the Prime Minister was the front man for the Leave campaign. Even his inability to get Britain out on October 31 — or, as he promised, to 'die in a ditch' if he failed — has not hurt him among most Leave voters.
There are other issues. Nobody doubts that Johnson, who wrote a book about Churchill, quoted Rudyard Kipling when he visited Burma and criticised Barack Obama for disliking the British Empire, is a patriot to his fingertips.
And given that Corbyn has consistently supported Britain's enemies, sympathised with the IRA and even talked of dismantling the Armed Forces, it is hardly surprising that so many patriotic Labour voters are planning to jump ship.
But there is more to it than Brexit, or even an anti- Corbyn backlash. The truth, as almost everybody in politics grudgingly admits, is that Johnson has the X Factor.
Six years ago, novelist Jonathan Coe wrote a remarkably prescient essay arguing that the key moment in Johnson's rise was his first appearance on the BBC One panel show Have I Got News For You. For Coe, very far from being a Boris fan, this was the moment the future Prime Minister cemented his public image as a 'loveable, self-mocking buffoon', an everyman rather than an Etonian.
He made people laugh, but he laughed at himself, too, pretending to be stupider than he actually was. And although the audience knew exactly what he was doing, they laughed nonetheless.
In an age of robotic, bland politicians, frightened of looking silly or saying anything controversial, that made him stand out.
Even his outspoken newspaper articles cemented his reputation as a free spirit, who refused to be shackled by the po-faced, politically correct thought police.
By and large, Johnson has stuck to that relentlessly good-humoured, self-deprecating formula. His most celebrated moment as London Mayor, for example, came when he celebrated Britain's first gold medal in the 2012 Olympics by taking to a zip-wire, which got stuck, leaving him dangling ludicrously while clutching two Union Jacks.
Trapped in his harness, a safety helmet jammed on his blond mop, he looked absurd — and that, in a sense, was the point. He was not afraid to look ridiculous; rather, he embraced it. It was later alleged that this was a deliberate stunt.
As a result, people have always felt comfortable with him. There is nothing starchy or censorious about him: quite the reverse. Among many voters his frankly disreputable private life probably works in his favour. People rarely enjoy the company of saints, but never mind meeting another sinner.
No wonder, then, that Johnson performs well in what American political scientists call the 'beer test', on the premise that the winner of the presidential election is usually the candidate with whom voters would rather have a drink.
He is well cast, then, as the spiritual heir to those 19th-century Conservatives who argued that the best way to win over working-class voters was to offer them 'Beer and Britannia'.
Under a patriotic, flag-waving Tory government, they proclaimed, working-class voters would be able to enjoy the pleasure of a pint, free from interference from teetotal Left-wing do-gooders.
(For some reason I can't help thinking here of Corbyn, who is patently ashamed of being British and touches only 'coconut water and apple juice'.)
In this respect, the comparison with Johnson's hero, Churchill, is spot on. Nobody loved waving the flag more than Winston. And he certainly enjoyed a drink, though it is admittedly difficult to imagine him ordering a takeaway curry.
Like Johnson, he refined his image, endlessly practising his supposedly spontaneous quips. He, too, had conspicuous flaws, drank too much, told tall tales, made off-colour remarks and played to the gallery.
We often forget that despite Churchill's aristocratic background, he entered Parliament in 1900 as the Conservative MP for the Lancastrian working-class mill town of Oldham.
A celebrity for his exploits in South Africa, where he escaped from a Boer prison camp, Churchill played the Beer and Britannia card for all he was worth, entering town in a cavalcade 'through streets crowded with enthusiastic operatives and mill girls'. He held the seat until 1906, by which time he had switched parties and moved to Manchester North West — another Northern seat.
And where was Johnson campaigning yesterday morning? You guessed it: Oldham, where almost two thirds of residents voted Leave.
We also forget, incidentally, that the kind of people who cannot stand Johnson often loathed Churchill, too. To earnest, high-minded, privileged sorts, Churchill seemed vulgar, demagogic and reactionary: an adventurer, not a statesman. Sound familiar? Yet many working-class voters loved him for it. They relished the performance; they admired his vigour, his optimism, his irrepressible humanity.
Above all, Johnson reminds me of Denry Machin, the central character in Arnold Bennett's marvellously funny 1911 novel The Card. Denry is a showman, a chancer, whose antics propel him from being a washerwoman's son to become the youngest mayor in his town's history.
He is unreliable, but his sheer spirit means most people like him. At the end of the book, when he has become mayor, one of his local fans chuckles: 'What a card! He's a rare 'un, no mistake.'
'And yet,' says a local councillor, 'what's he done? Has he ever done a day's work in his life? What great cause is he identified with?'
'He's identified,' says the first man, 'with the great cause of cheering us all up.'
That is Mr Johnson to a tee. A bit of a card, a bit of a chancer, but dedicated to the great cause of cheering us all up.
Given the alternative, let's hope he's still smiling on December 13.