Retail specialists call it an impulse purchase: that little ‘thing’ that wasn’t on your shopping list. With the surprise package or the mystery cart comes the excitement of the game of chance.

We could see in this new fashion an additional, and fun, variation of the circular economy. But on closer inspection, this outbreak is not so encouraging, writes Simon Tisdall, the author of The Circular Economy: How We Made Our Way To A Sustainable Economy.