It's not really that perilous to travel from the US to the UK, unless you're in a step challenge.
This past week, I was traveling for almost 40 hours—including 14 yesterday thanks to ordinary aviation delays. When you're on a plane, it's pretty hard to get steps. Fortunately the time change from the UK back to the US is in my favor, so I got 6 extra hours in which to walk, and I also got Parker back. Still, I barely squeaked in with 10,689 for the day and an unusually low 81,638 for the week (helped immensely by Wednesday's 18,319).
The nadir, of course, was last Sunday, when I flew to London. The lost 6 hours occurred right in the middle of the day, so not only did I get the fewest steps (7,407) since June 11th (7,044), but also this happened:
So naturally, I walked to work today. I'm already at 9,770 and heading towards 20k (assuming I walk home, too).