Boris Johnson has faced a political life full of challenges but now faces his toughest one yet

His artist mother Charlotte suggested the remark was related to her own breakdown, saying: “I often thought that the idea of being world king was a wish to make him unhurtable, invincible somehow, safe from the pains of life, the pains of your mother disappearing for eight months, the pains of your parents splitting up.”

Vulnerability is not something one associates with the Prime Minister and, perhaps, the thought of giving into the coronavirus and so continuing to work long hours in Downing St despite its debilitating symptoms may, ultimately, have landed him in an intensive care unit in a London hospital.

However, humour, or attempts at it, is something that, to his own detriment sometimes, one does associate with the idiosyncratic Mr Johnson.

Having repeatedly said he was as likely to become PM as to be reincarnated as an olive, in a 2013 documentary he gave the game away and his not-so-secret ambition, albeit lower than world king, was publicly admitted to.

He told the distinguished political documentary-maker Michael Cockerill: "If the ball came loose from the back of the scrum, which it won't of course, it would be a great, great thing to have a crack at."

Of course, within three years the ball would indeed emerge and, although, he would at the first attempt fumble it, within another three he would seize it.

Controversy has been Mr Johnson’s constant companion not least in his private life.

With two failed marriages behind him, he has either five or six children depending on which profile you read. His premiership was initially dogged by stories about his granting financial favours to and having an affair with US model-turned-businesswoman Jennifer Arcuri. The PM steadfastly refused to comment on the matter beyond denying any wrongdoing.

For a politician, who is loved and loathed in equal measure, Mr Johnson has, despite many setbacks, become: an MP, twice; London Mayor, for two terms; Foreign Secretary and Prime Minister as well as, of course, leading the successful Brexit campaign when the odds appeared heavily against it.

So, success has followed ambition but its course has never been straightforward.

New York-born and having had a peripatetic childhood - his father Stanley’s work for the World Bank and the European Commission among others meant young Boris had moved house 32 times before he was 14 – an Eton scholarship was followed by reading classics at Oxford, where, notoriously, he became a member of the hard-drinking Old Etonian Bullingdon Club.

His membership captured one of the more famous images of his youth as he stood next to a contemporary toff, David Cameron, who would, of course, precede him into Downing St.

After college, family connections helped Mr Johnson launch a career in journalism, although he got off to a false start. He was fired by The Times for inventing a quote. However, whether by luck or resilience, he fell on his feet and secured a job at the Daily Telegraph, where for five years he was the paper’s Brussels correspondent, establishing himself as a leading Eurosceptic.

Controversy, of course, would follow him wherever he laid his hat. And when he returned to London to become a political columnist, his turn of phrase entertained and shocked in equal measure; he infamously described Africans as “piccaninnies” with “watermelon smiles”.

After he became editor of the right-wing Spectator magazine in 1999, more controversy followed, most notably when he published an editorial suggesting drunken Liverpool fans were partly to blame for the Hillsborough tragedy.

Politics beckoned. Following a failed attempt to become the Conservative MP for Clwyd South in 1997, he succeeded in 2001 in the Tory stronghold of Henley, following in the footsteps of Michael Heseltine, who, as an arch-Remainer, would later become one of Mr Johnson’s fiercest critics.

When Michael Howard became Tory leader following the party’s 2001 election defeat, he made the ambitious backbencher Shadow Arts Minister. Yet within six months he had sacked him after it emerged the new recruit had had an affair with Spectator columnist Petronella Wyatt, which had resulted in two terminated pregnancies.

But in March 2007, the PM’s insuppressible ambition rose up again when he announced his candidacy for London Mayor. Initially not taken seriously, he suddenly gained Mr Cameron’s approval when the early favoured candidate Nick Boles withdrew. Within a year he had defeated Labour’s Ken Livingstone to become the capital’s leader.

After two terms, projects like Crossrail, the 2012 Olympics, Boris bikes and new Routemaster buses, a poll after he had stepped down in 2016 suggested 52 per cent of Londoners believed he had done a good job. But one enduring image of his mayoralty was Mr Johnson dangling helplessly from a zipwire over the Olympic park.

Another year and another challenge and more success as he became MP for Uxbridge at the 2015 General Election.

But another gigantic battle lay ahead in the EU referendum campaign during which he became the pro-Brexit campaign’s figurehead.

Against the odds, and despite highly contentious claims such as a £350 million a week Brexit dividend for the NHS, the Leave campaign won the 2016 poll; its historic victory unleashed three years of political turmoil at Westminster.

One of the victims was Mr Cameron who swiftly resigned, sparking a Tory leadership contest, where Mr Johnson emerged as the frontrunner.

But in a dramatic twist of events, his fellow Leave campaigner, Michael Gove, unexpectedly threw his own hat in the ring and declared his colleague could “not provide the leadership or build the team for the task ahead". The Scot was dubbed an “assassin”.

It was a shattering blow and in a rare show of vulnerability a wounded Mr Johnson withdrew from the contest, which was ultimately won by Theresa May after Andrea Leadsom, whom he had supported, withdrew.

Nonetheless, the new premier appointed her erstwhile rival as Foreign Secretary, seen by some as a move to neutralise Mr Johnson in the forthcoming Brexit negotiations as his role would be overshadowed by the new Brexit and Trade Secretaries.

Needless to say, more controversy followed his new appointment; not least over the imprisonment as an alleged spy of the British-Iranian Nazanin Zaghari-Ratcliffe, whose plight was not helped when the Foreign Secretary declared she had “simply been teaching people journalism”.

But by July 2018, the mounting tensions over Mrs May’s Brexit strategy proved too much for Mr Johnson and his fellow Brexiteer David Davis and both resigned from Cabinet.

Within days Mr Johnson had signed a contract to write for the Daily Telegraph and penned more controversial articles, one of which included a reference to how under Mrs May’s leadership the UK had “wrapped a suicide vest around the British constitution and handed the detonator to Michel Barnier”.

Another line in another article in which Mr Johnson criticised a Danish law banning Muslim women from wearing the Niqab got him into even hotter water after he likened women who wore the veil to “letter-boxes” and “bank robbers”.

After Mrs May could no longer fend off the internal pressure in the Tory Party for her to go, Mr Johnson decisively put himself forward and by July 2019 finally caught the ball as it came out of the scrum, becoming Tory Party leader and PM.

His pledge to get Britain to leave on October 31 “no ifs, no buts” fell foul of the Commons, which took back control and frustrated Mr Johnson, whose decision to prorogue Parliament was declared unlawful by the UK Supreme Court.

It was only when all the parties finally agreed a General Election was the only way forward and the Tories secured a famous victory on the back of “Get Brexit Done,” delivering Mr Johnson a Commons majority of 80, that the political impasse was finally broken and Britain left the EU on January 31 albeit with an 11-month transition period.

Yet within three months the PM’s grand plan for a One Nation Government, including tax breaks, more public spending and securing the Union by blocking a second Scottish independence referendum, was overshadowed as the country was hit by another more significant challenge than even Brexit.

The coronavirus pandemic was an unseen and unexpected enemy, confronting Mr Johnson with yet another huge challenge, which has involved an unprecedented restriction of personal freedom and unprecedented spending pledges for businesses and workers to see the economy through the crisis.

But, of course, it is now involving directly his own future as the PM struggles to battle for the return of his health.

As the tributes and messages of support flowed in following his hospitalisation, colleagues and friends have put great store by Mr Johnson’s ebullience and strength of character, which have seen him through many ups and downs and they believe will see the 55-year-old Tory leader through his latest, and possibly, greatest personal challenge.

Mr Gove extolled his colleague’s “zest for life” and described him as a “force of nature, a bundle of energy, determined to do the very best for the country that he loves”.

At the daily Downing St press conference, Dominc Raab, deputising for the PM, said: “I'm confident he will pull through because if there is one thing that I know about this Prime Minister is he is a fighter and he will be back leading us through this crisis in short order."

Will Waldon, Mr Johnson’s former press chief when he was London Mayor, insisted he was far fitter than he looked, describing him as a “really strong guy”.

In a message of hope, he added: “He will whip anybody's backside on a tennis court, he runs regularly, he doesn't smoke, he drinks moderately. So, if anyone is in a good position both physically and mentally to fight off the disease, then the Prime Minister is that person."

Political friend and foe alike are praying he is right.