In September 2019, just two months into his tenure, there was gleeful speculation among Boris Johnson’s enemies that he might become the shortest-serving prime minister in British history.

Faced with an impossibly divided and paralysed House of Commons, a Conservative Party riven by internecine warfare and a defiant European Union, it was entirely plausible that Mr Johnson might be gone within weeks.

Instead, the Prime Minister’s hitherto underappreciated ruthlessness, combined with his well-known common touch, saw him bulldoze the Gordian knot of Brexit, purge the party of opposition and storm to the largest Conservative majority since Margaret Thatcher in 1987.

There are now 17 former prime ministers with shorter tenures than Mr Johnson. And yet, barely two years on from that electoral triumph, he faces leaving office sooner than either Theresa May or Gordon Brown – two figures frequently associated with failure in Number 10.

Mr Johnson’s place in the history books is assured, thanks to his roles in precipitating and then completing Brexit and in Britain’s handling of the pandemic. His spectacular, if so far incomplete, fall from grace might add a third reason.

If he resigns in the next few weeks, it will be a downfall without modern precedent.