Ronald Reagan probably didn't realize he was starting a tradition when he wrote a note congratulating his successor and left it in the Oval Office desk drawer after two terms as president. He did that for George H.

US President Donald Trump has shared the contents of a letter that his predecessor Joe Biden left in his Oval Office desk this week. Mr Trump had to be reminded of the long-held tradition that departing presidents tend to leave letters to their successor when he returned to office on Monday.