Ben Lowry: Boris Johnson wanted to be king of the world, so maybe he is first eyeing up a run at the White House

He also drew laughs by saying that he would become a booster rocket, who will “come down invisibly in some remote and obscure corner of the Pacific”.

But could these strands of good humour be woven together to reveal the outline of an elected comeback in the land from ‘sea to shining sea’ (ie in America, which stretches from the Atlantic to the Pacific)?

Mr Johnson was born in the United States, and for a man who wanted to be ‘king of the world’ that superpower offers the next best thing — the most powerful political office on the globe, that of US president.

To qualify for being so, you have to be a ‘natural born citizen’ of the USA, which has over the centuries been taken to mean people born in the 50 states. This meant, for example, that those towering American figures of public life, the presidential advisor Henry Kissinger and the ex governor of California Arnold Schwarzenegger, could never be president — both US citizens, but the former born in Germany, the latter in Austria.

In recent years there have been political efforts to define the meaning of ‘natural born citizen’ but there has never been any doubt that if you emerged into the world in a place such as New York, as Mr Johnson did, you qualify.

A conspiracy theory emerged that Barack Obama had not in fact been born in Hawaii, and thus was not a legitimate president, but I am not aware of any such doubts about the birth certificate of the UK’s outgoing prime minister.

I know something about all this because I too was born in the mainland US, in the state of Maine. But I have spent most of my life in Northern Ireland.

I sometimes say I was born in Bangor Maine (where the horror writer Stephen King lives) and grew up in Bangor Northern Ireland (where the late Ulster political leader David Trimble was born). It isn’t quite true, I was born in Portland, a drive from Bangor, but I did spend my childhood in the other Bangor.

Like Mr Johnson, I am a dual citizen with British and American passports, something many nations do not allow, but which both the US and UK do.

Like Mr Johnson, I would qualify to stand for election to the White House (the other requirement being that you have to be aged 35, a milestone both of us passed some time ago).

In Mr Johnson’s case though the notion is not entirely fanciful.

He is better known in the US than any other contemporary British politician (although that is not saying much because almost all are utterly unknown). But he does have sufficient name recognition that the popular right wing Fox TV host Tucker Carlson can refer to Boris Johnson by name without feeling the need to elaborate much to viewers on who he is.

As an ex prime minister Mr Johnson could earn several million pounds by making speeches and writing books, but nowhere near enough to sustain a presidential campaign.

Perhaps though, if he has American ambitions, he could launch them by first running for the US senate, in a state such as his birth one of NY. The senate is the prestigious senior chamber of the American legislature and a launching pad for a later run at the US top job.

There is one peril to being a dual US-UK citizen with which Mr Johnson is familiar. After a certain point in some types of high income you can be liable to certain taxes in both jurisdictions. He sold his London home for a fortune, which as his main home was exempt from UK capital gains tax, but was presented with an American tax bill. After protesting that this was “outrageous”, given that he hadn’t lived in the US since childhood, he paid up.

By doing so, was this man of overweening ambition trying to keep alive a transatlantic political ambition? In fact it was reported around the time of Brexit in 2016 that he had renounced his US citizenship.

Could he get it back? Apparently that is hard, but he will always have been born there.

In any event there is one more snag for a politically ambitious person who was born in the US. To become US president, you have been resident in the nation for 14 years.

In Boris’s case, that would mean in addition to his childhood years spent stateside he would need to live there for another decade. Aged 58, he would be late 60s before becoming fully eligible for the Oval Office.

Too old to be America’s commander-in-chief? Not quite. Ronald Reagan was 69 on becoming US head of state, Donald Trump 70 and Joe Biden 78.

Maybe Mr Johnson hopes to resettle across the Atlantic. Maybe he could argue that he never renounced his citizenship, in the same way that he never agreed an Irish Sea border.

And perhaps, if he wants to build a life in America and clock up the years there, he should host a US TV show, in the tradition of those Englishmen Piers Morgan and James Corden ... and that American Scot, Donald Trump.

• Ben Lowry is editor of the Belfast News Letter (that is Belfast Northern Ireland, not Belfast Maine)

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