Last week, I met Fred Finn, who is officially the world's most travelled person. He has been in the Guinness Book of Records since 1983 and has now flown 15 million miles - the equivalent of 31 trips to the moon. He made 718 trips on Concorde and always sat in the same seat - 9a - because, he told me last week, "It was the first row to be served from the back galley, so I got served first and, before I got on, the crew used to put a little kettle under my seat with Dom Pérignon in it. They used to change it three times during the flight, so I got a bottle-and-a-half of DP for my lunch on the way to New York."
Fred has visited 139 different countries but not North Korea.
"I don't really want to go there," he says.
And why should he?
"I've been held hostage in Iran during the Revolution," he told me, "I've had bombs on board and I've landed without the wheels down."
It was very cold in Esher last week, so Fred persuaded a local pub which was closed to open just for us so we could have a seat. He is very persuasive.
In his youth, Fred was a professional cricketer. Later, he advised Richard Branson on the start-up of Virgin Atlantic. He also helped arrange Mikhail Gorbachev's lecture tour of the UK, Sarah Feruson's charity trips to Kenya and was a friend of country singer Johnny Cash. Any man who can tell first-hand anecdotes about Adnan Khashoggi is someone I will always happily have tea with in a pub in Esher.
Indeed, Ukraine Airlines are soon to start an online magazine called Fred Finn Destinations.
But the strange thing is, with 15 million flying miles under his belt, Fred does not believe in jet lag.
"I don't believe in it at all," he told me. "You never got jet lag on Concorde and you went through five time zones.
"I believe that, if you sit in a flying aluminium tube for over five hours, you get dehydrated, your eyes get dry and your skin gets dry and you get tired because of this. I've found that, if you keep water - a little spring water spray - on your eyes and face, you don't get jet lag."
"But it's not jet lag," I said. "Really, it should be called time-zone lag."
"Well, it's a 'tired' lag," said Fred. "But I don't get it. When I get on a plane, I set my watch to the time zone I'm going to and I eat accordingly.
"When I get off the plane, I stay up until the local going-to-bed time and then I sleep well and I get up in the morning like nothing happened. I know that works for me, because I was doing it every week for Christ knows how many years."
"But," I said, "if you fly from London to Beijing, your body clock is all out of kilter."
"But is it?" he asked. "I didn't get that.
"You should also take into account, if you're flying to China, how long your day has been. You are putting in a day and a half on a long-haul flight but, if you keep yourself moisturised and live in the time zone you are going to...
"Some people get on a flight from London to New York in the morning and they eat breakfast. I won't take breakfast leaving London because it is lunchtime in New York - so I eat as if it were lunchtime. By the time I get to New York, I've already lived in that time zone for six or eight hours - the flight is around six hours in one direction and eight in the other because of the jet stream - it changes in March and November."
"There's so much hype about so-called jet lag and about deep-vein thrombosis on long haul flights
"I wrote an article 25 years ago called Aerial Isometrics.
"It's about how to sit in your seat and do exercises without anybody seeing you. Just by clenching the muscles in your leg. And that stops the problem. People said there was no such thing. Then they started selling socks to stop it and there was a big deal about it."
I am not sure about jet lag, but who am I to argue with the world's most travelled person? I do know I was once on a long-haul flight where I got three breakfasts because it was breakfast time in each time zone when we were due to have a meal. That really confused my body.
I suspect it was cheaper for the airline than serving lunches or dinners.
We live in an uncertain world.