Lads come into the store and offer to pay for goods with money they have stored in their socks or shoes. It’s happening in Christopher Wilde’s Yorke One Food Store on a council estate in Newark, Nottingham, and he would like to know if this is a widespread trend. “Seems to have been a trend for the past six months or so,” says Christopher, “mainly with 15- to 30-year-olds, mainly English.”

He has asked a few of them why and they mumble something about losing money out of their pockets.

I suggested that it might be because they are afraid of having their pockets picked. Christopher says these lads look like they can stand their ground quite well.

He has asked around locally. One shopkeeper in town said she had noticed it a few times, but not nearly as often. Another said they had seen it once or twice in supermarkets.

He also asked some of his customers how they would feel about accepting change that had been walking around in someone’s footwear. They didn’t think much of this idea. “It’s unhygienic,” says Christopher.

“So we’ve now put a notice up saying ‘We are not obliged to take money that has been stored in your shoes or your socks’.”

I mentioned this to my next-door neighbour, a retired policeman who used to be with the Met. He had just one word to say on the subject: “Drugs.”

Either way it sounds like ‘dirty money’; not that notes are ever particularly clean and only ever get washed by mistake.

But how widespread is it? (This is where you come in.)