Some years ago, in 2002 I think it was, I happened to be passing through Los Angeles airport on my way for a flight back home. Airport security was considerably tighter than it used to be, but all those incredibly annoying scanners had yet to be installed.

I was randomly selected for a baggage check. (The fact that not all bags were checked tells you how long ago this was.)

Fine. I handed over my bag.

They opened it up, had a poke around, then swiped the inside with a small piece of material which they popped into a machine.

Red lights flashed! Alarms sounded! Nice men with guns appeared!

"What's wrong?" I asked.
"Sir, please step back behind the red line," said a nice man with a gun.
I stepped back behind the red line.
"What's wrong?" I repeated.
"Sir, your bag has tested positive for chemical explosives."

Well this was going to be fun! I knew I was pure as the driven snow, in this one small respect at least, so I settled in for an interesting experience.

It will come as no surprise that everything came out of the bag. Then they pulled the frame out of the bag. Then they looked inside the frame. Then they looked inside the lining. All clothing was minutely inspected. I had probably 15 or 20 books in that bag, some of them huge technical volumes. They turned every single page.

While this was going on, another nice man took my passport and wandered off with it, no doubt to ask the FBI if I was known to them. He returned while they were still flipping pages and tearing my laptop apart. He gave me a strange look, and didn't return the passport.

That's when I remembered that, not long before, I'd had to get a Federal Police security check.

The check was so I could do some work at Argyle Diamond Mine, which is the largest source of pink diamonds in the world. Once you're inside the compound, the diamonds are just lying on the ground, so they prefer to restrict visitors to honest people and successful thieves who haven't been caught yet. (While walking past swept-up heaps of small black rocks, I'd asked, "Where are the diamonds?").

But the nice men at LAX wouldn't have known that detail. All they would have known was that the Australian Federal Police had queried the FBI for a standard check on me, and the FBI had probably recorded that query. And now here I was, testing positive for chemical explosives.

After they had reduced the bag to its component atoms, they asked, "Have you ever spilled any soap or washing powder in this bag?"

As it happened, my wife and I had used this bag on our honeymoon, and washing powder had indeed been spilled. Fourteen years before.

"That must be it, then. The machine detected the phosphorus."

From fourteen years ago?

They reassembled the bag and repacked. I tried to help several times, but each time was politely but firmly told to get back behind that red line. So I watched them make a complete hash of the repack. Lumps bulged in odd places and the zipper strained. They handed back my passport. I moved to pick up the bag, but was told, "No sir, this man here--" they indicated one of their own, no doubt the most unimportant man present, "--this man will carry your bag until you get on your plane."

My new friend was having none of that. He picked up my bag, brushed past the long queue of people waiting to check in, and stopped at the front desk.

"Check this passenger in at once."

And that's how to get to the head of the queue at LAX. But I wouldn't necessarily recommend it. We threw away the bag when I got home.