After all the worrying by the U.S. media and U.K. politicians, day one of President Trump's state visit to Britain has been a smashing success.

For a start, President Trump appears to have mastered the complicated art of British royal protocol. Trump followed Queen Elizabeth II's lead, laid a wreath at Westminster Abbey (Britain's de facto Arlington Cemetery), and took high tea with Prince Charles at Clarence House.

There were reasons to worry things would go poorly.

Prince Charles, the Queen's son and next in line to throne, for example, has criticized Trump's climate change policy. London Mayor Sadiq Khan launched simplistic and personal attacks on Trump. Trump responded with a typical insulting tweet. But since landing, Trump has created no drama. Trump nodded respectfully in his meeting with Charles.

As evening begins, Trump's tweet below will have surely sparked a smile on British government faces.