Dear Joe … Will Trump leave Biden a traditional congratulatory letter?

George HW Bush called a smooth transition between the outgoing president and his successor the "majesty of the democratic system".

Nothing befits a US leader as the grace he sets in leaving office. Not for the first time, Donald Trump appears poised to tear up the presidential playbook.

All eyes are now on what kind of parting message Mr Trump sends if he loses to Joe Biden. For all its screeching U-turns, endless shocks and jaw-dropping scandals, politics is equally as renowned for its traditions.

One such is that the outgoing US president leaves his successor a letter offering both congratulations and various pearls of wisdom accrued from their time in the Oval Office.

When President Barack Obama stepped down from office, he even referenced the epistolary custom when addressing the nation.

But it is now under existential threat. The 2020 US elections have been characterised by rancour and unrest not seen since, well, the 2016 US elections.

And with Mr Trump vehemently alleging he is being cheated out of the White House, it seems hard to believe he will set aside his rage to pen a conciliatory missive should his defeat transpire.

If he does, perhaps he will adopt the block capitals style that has recently been exhibited in his frenzied tweets?

One thing that you can predict about Donald Trump, however, is that he is always unpredictable. His would certainly be a memorable addition to the cache of letters exchanged between erstwhile US Commander in Chiefs.

Self-professed letters lover @LettersofNote tweeted the last four:

The former British Prime Minister, Harold Wilson, once said that "a week is a long time in politics".

As adages go, it is a hard one to contest, and the febrile last seven days in the race to become America's next president are a stark reminder of its enduring relevance.