As the foreign secretary, it's not surprising to learn of Johnson's enthusiasm for Trump's visit. After all, the two are big supporters of Brexit and, after Trump's election, Johnson called it a "moment of opportunity".
However, Johnson's tone has changed considerably since December 2015, when the Conservative MP strongly criticised Trump for his comments about supposed areas of London that had been radicalised.
In an interview with MSNBC at the time, Trump said:
We have places in London and other places that are so radicalised that police are afraid for their own lives.
Johnson - who was Mayor of London at the time - quickly shot down that rhetoric, denying Trump's claims and branding them as "simply ridiculous".
The Telegraph quotes him as saying:
Donald Trump's ill-informed comments are complete and utter nonsense.
As a city where more than 300 languages are spoken, London has a proud history of tolerance and diversity and to suggest there are areas where police officers cannot go because of radicalisation is simply ridiculous.
I would welcome the opportunity to show Mr Trump first hand some of the excellent work our police officers do every day in local neighbourhoods throughout our city.
He also went on to directly attack Trump by claiming the only reason he wouldn't want to go to some parts of New York would be the risk of bumping into the current president.
Crime has been falling steadily in both London and New York - and the only reason I wouldn't go to some parts of New York is the real risk of meeting Donald Trump.
This dramatic U-turn from Johnson hasn't gone unnoticed:
Does Boris Johnson's hypocrisy know no bounds?
"The only reason I wouldn't visit some parts of New York is the rea… https://t.co/vzQtuC3GUB