I have to go to Arizona to attend a lecture. It is a long way to go for a single day’s event, so I tack on a few extra days and arrange to go the Grand Canyon.

My driver is a retired police officer, and as we reach the outskirts of Flagstaff a pungent smell fills the car. I ask him what it is.

He laughs. “I’ll tell you what it is. It’s skunk, that’s what that is.”

“Skunk?” I enquire.

“Skunk,” he says “a potent new strain of cannabis. There is a lot of it around these days.”

As we reach the centre of town the smell becomes almost unbearable.

“It is incredible,” he went on. “There must be a huge skunk farm round here. It is incredible they think they can get away with it, in the middle of a big town. And what are the cops doing? They only have to follow their noses to make a bust.”

We reach the traffic lights right in the centre of Flagstaff and there, lying squashed in the middle of the road, is a dead skunk.

We burst out laughing. He grins ruefully “well, I guess there’s a reason it’s called skunk.”

The smell is impossible to remove, and the car stinks of skunk for the rest of the trip.