President Trump's visit to London last week caused some raised eyebrows when his custom 747 landed not at London Heathrow, but at London's #3 airport, Stansted, best known as Ryanair's home base.
But it wasn't a diplomatic diss, it turns out. That's also where the plane landed when Pres. Obama was aboard. The last U.S. president to land Air Force One at Heathrow was George W. Bush, and the security arrangements at the crowded field resulted in traffic jams and 63 flight cancellations.
Stansted, on the other hand, has unused runway capacity, and plenty of space to land, disembark and wait, all out of sight of the main terminal. When the Queen travels, it's usually the Royal Air Force base at Northolt, but it's not big enough to handle jumbo jets.