Boris Johnson, the far-ahead front-runner to become Britain's prime minister this week, waved a vacuum-packed fish over his head and railed at the European Union.

A kipper smoker on the Isle of Man, Johnson said Wednesday, "has had his costs massively increased by Brussels bureaucrats who have insisted that each herring fillet must be accompanied by" - he paused to reach for another prop - "a plastic ice pillow! Pointless, expensive, environmentally damaging, health and safety."

The audience roared. Johnson, populist charmer, always gets a laugh.

Did it matter that the ice pillow was actually the result of a British regulation and had nothing to do with the EU? Does it matter that the likely future British leader has a loose relationship with the truth?

The key to understanding Johnson, say his biographers, lifelong observers, friends and enemies in a dozen interviews with The Washington Post, is to see him first as a hack - a hack being the self-deprecating but not pejorative Britishism for a working journalist shovelling reams of copy to his masters on deadline.

Johnson was fired from his first job, at The Times of London, for making up a quote about Edward II's catamite lover and attributing it to his godfather, the Oxford historian Colin Lucas.

But he would go on to find his voice, and develop his shtick, during his years as a Brussels-based foreign correspondent - racing around in his lipstick-red Alfa Romeo, speaking intentionally bad French and banging out outrageous and only semi-true dispatches.

Before he was a lawmaker, London mayor or foreign secretary, Johnson made his name as one of Britain's top columnists. And he has continued as a hack through much of his political career. A possible last column ran just a week ago.

It was as a hack, writing for the middlebrow "Tory Telegraph," that Johnson learned to combine his high and his low. He is an upper-class Oxford-educated classicist who sprinkles his rapid-fire remarks with Latin aphorisms.

But he has also cultivated a persona as a populist everyman in frayed trousers who bikes to the office. He is a version of his favourite meal: links of proper British sausage quaffed with $100-a-bottle Tignanello.

It was as a hack, too, that Johnson stoked the cheeky, slanted, self-pitying euroscepticism that would set the stage for Brexit - and ultimately send him in the direction of 10 Downing Street.

"Beware of newspaper columnists," Martin Fletcher, a former Times editor, said. "They are paid to be controversial, to be colourful, to be provocative. There are very few consequences to what they write. But those are not attributes you want in your prime minister."

The ranks of the British political class are full of former journalists. But Johnson - if he bests Foreign Secretary Jeremy Hunt when the results of the leadership race are announced Tuesday - would be the first hack in the top job in recent times. In this, he is thought to aspire to be like Winston Churchill. Johnson, by all accounts, has never been lacking in ambition.

Boris Johnson developed a controversial reputation among colleagues as a journalist before he entered political life (Reuters)

Hardly anyone had heard of him when 24-year-old Johnson arrived in Brussels in the spring of 1989 to begin life as a foreign correspondent for The Telegraph. He and his new first wife moved into an inauspicious flat above a dentist's office in Woluwe-Saint-Pierre, a bourgeois neighbourhood where fussy Flemish residents would scribble anonymous notes complaining about the misplacement of trash bins, according to his biographers.

By the time he left Brussels five years later, Johnson was one of Margaret Thatcher's favourite commentators - the banner man for a new type of Tory, an irreverent, kind of hip Conservative who would shortly launch his rocket of a political career.

In Brussels - the often dull, bureaucratic capital of the EU - the young Johnson found a way to run at the front of the field, ahead of older, more docile correspondents who tended to stick up for the EU and stick to the facts.

Johnson hit on a theme: that the European Union was run by the devilish French and rules-obsessed Germans, who were out to pass all sorts of onerous rules designed to clip the wings of a once-great Britain.

Skewering European officials at theatrical news conferences, then letting it rip on his Tandy 300, Johnson became the subject of envy and admiration in the British press corps in Brussels.

"His stories about the idiocies of the European Union were received with rapture by an ever-growing circle of fans, and he became the only Brussels correspondent of whom ordinary mortals have heard," wrote Andrew Gimson, a former colleague and author of a biography, "The Adventures of Boris Johnson."

But these same stories were viewed, by colleagues and competitors, as deeply dubious.

Peter Guilford, who worked alongside Johnson as a Brussels correspondent for The Times, credited Johnson with turning eurosceptic journalism into "an art form." But Guilford took issue with Johnson's willingness "to ham up the story, so there wasn't much difference between news and entertainment. . . . He would write outrageous stories with only slenderest connection of truth in them."

Boris Johnson in profile

Fletcher, the former Times editor, has compiled a list of Johnson's greatest hits from Brussels: Johnson wrote that the EU wanted to standardise coffins, the smell of manure and the size of condoms - and had rejected an Italian request to make undersized rubbers. He warned Brits that their prawn-cocktail-flavoured chips could be banned, that their sausages were under threat and that their fishermen would be required to wear hairnets.

Further goosing fears of the supranational state, Johnson wrote about the coming of compulsory European identification cards. (They are not coming.) He speculated that French, German and Dutch citizens would be elected to the British House of Commons. (Also not happening.) And he sought to underscore EU wastefulness with his description of a "kilometre-high Tower of Babel" to be built in Brussels.

James Landale, who worked with Johnson in Brussels and is the BBC's diplomatic correspondent, wrote a poem to mark Johnson's departure from the EU capital in 1995: "Boris told such dreadful lies / It made one gasp and stretch one's eyes."

Johnson has acknowledged that there was a bit of a game in all this.

"Everything I wrote from Brussels I found was sort of chucking these rocks over the garden wall," he told BBC's "Desert Island Discs" in 2005. "And I listened to this amazing crash from the greenhouse next door over in England. It really gave me this, I suppose, rather weird sense of power."

Johnson and his spokesman did not respond to requests for a comment.

Bill Newton Dunn, a long-serving British member of the European Parliament, said that, in person, Johnson was like a "puppy dog, anxious to please and get on with everybody."

But less so in print.

"What was irritating is that he then started coming up with some extraordinary and, it turned out, completely inventive untrue stories about Brussels," Newton Dunn said, recalling the headline: "Brussels recruits sniffers to ensure that Euro-manure smells the same."

His former editor at The Telegraph, Max Hastings, has declared Johnson "unfit for national office."

Biggest lies told by Boris Johnson Show all 5 1 /5 Biggest lies told by Boris Johnson Biggest lies told by Boris Johnson Made-up quote for The Times Johnson was sacked from The Times newspaper in the late 1980s after he fabricated a quote from his godfather, the historian Colin Lucas, for a front-page article about the discovery of Edward II’s Rose Palace. “The trouble was that somewhere in my copy I managed to attribute to Colin the view that Edward II and Piers Gaveston would have been cavorting together in the Rose Palace,” he claimed. Alas, Gaveston was executed 13 years before the palace was built. “It was very nasty,” Mr Johnson added, before attempting to downplay it as nothing more than a schoolboy blunder. PA Biggest lies told by Boris Johnson Sacked from cabinet over cheating lie Michael Howard gave Boris Johnson two new jobs after becoming leader of the Conservatives in 2003 – party vice-chairman and shadow arts minister. He was sacked from both positions in November 2004 after assuring Mr Howard that tabloid reports of his affair with Spectator columnist Petronella Wyatt were false and an “inverted pyramid of piffle”. When the story was found to be true, he refused to resign. PA Biggest lies told by Boris Johnson Broken promise to boss In 1999 Johnson was offered editorship of The Spectator by owner Conrad Black on the condition that he would not stand as an MP while in the post. In 2001 he stood - and was elected - MP for Henley, though Black did allow him to continue as editor despite calling "ineffably duplicitous" PA Biggest lies told by Boris Johnson Misrepresenting the people of Liverpool As editor of The Spectator, he was forced to apologise for an article in the magazine which blamed drunken Liverpool fans for the 1989 Hillsborough disaster and suggested that the people of the city were wallowing in their victim status. “Anyone, journalist or politician, should say sorry to the people of Liverpool – as I do – for misrepresenting what happened at Hillsborough,” he said. PA Biggest lies told by Boris Johnson ‘I didn’t say anything about Turkey’ Johnson claimed in January, that he did not mention Turkey during the EU referendum campaign. In fact, he co-signed a letter stating that “the only way to avoid having common borders with Turkey is to vote Leave and take back control”. The Vote Leave campaign also produced a poster reading: “Turkey (population 76 million) is joining the EU”

"There is room for debate about whether he is a scoundrel or mere rogue, but not much about his moral bankruptcy, rooted in a contempt for truth," Hastings wrote in the Guardian.

Conrad Black, who once owned the publication, fired back in the Spectator that Johnson is "more reliable and trustworthy" than Hastings.

Black had his own run-ins with Johnson, but he called his former charge "such an effective correspondent for us in Brussels that he greatly influenced British opinion on this country's relations with Europe."

"Boris's peccadilloes were more absurd, complicated and over-publicised than the shambles of the personal lives of other journalists," Black said. "But his editorial opinions were sensible and consistent. His shtick grew tiresome, like an over-familiar vaudeville act, but he was at all times a person of goodwill and his foibles were deployed to the benefit of the enterprise."

Sometimes, when Johnson's words haven't been supported by facts, people have excused him with the notion that he's inattentive to detail. But Guilford emphasised that Johnson isn't lazy: "He's a workaholic. I've never seen someone so committed at the expense of everything."

He recalled the two were at a mutual friend's wedding in Ireland, and Johnson "spent every waking minute talking to Irish people" about their views on an upcoming abortion referendum.

"On Monday, we all woke up with a hangover to see this big centre page piece about the referendum. He spent the whole time doing it - irrespective of being there with friends and family," Guilford said. "In my view, he never stops."

Sonia Purnell, author of "Just Boris: A Tale of Blond Ambition," was Johnson's deputy in the Brussels office.

In her words, working alongside Johnson "wasn't fun and it wasn't productive. He's very secretive, he's really difficult to work with for that reason." She said that he has a "frightening temper" and there's "no team playing. He's very much the solo performer."

Boris Johnson blimp flies over Parliament Square as anti-Brexit protesters gather for major march

In her biography, she recalls Johnson launching into closed-door rants just before deadline, screaming obscenities at a potted plant, to lather himself up to write another scathing column.

She characterised Johnson as very competitive - suggesting that, going back to his childhood, he "competed at everything, including who was the blondest, who was the fastest, who was the cleverest." In the adult Johnson, she said, that has resulted in a desire for "approval and love of the crowd" and an "incredible drive to be top dog."

Ms Purnell claims she once said something to Johnson - made a joke about an official - in the kitchen of The Telegraph's Brussels bureau. She saw her remarks in print a few days later. Johnson attributed them to "an EU source."