If you are reading this article online, perhaps you could go to the comments section and let us know what single slightly unusual item you have bought which has brought you the most reliable and lasting happiness.

Perverse answers are welcome, of course, but I am not so interested in suggestions such as ‘a Thai bride’ or ‘a brewery’ or ‘“The Concert” by Johannes Vermeer’. What I am hoping for is a list of slightly unusual domestic or practical items which you might have bought on a whim or as a slight extravagance but which subsequently you found surprisingly delightful or life-changing to the point of boring your friends about them.

My first two suggestions would be the air fryer (a device which fries food without using oil) and an ice-making machine which sits in the kitchen making ice cubes so I can make a gin and tonic in under a minute.

But far above even these two devices on the happiness-per-pound-spent graph would come a thing called a ‘mattress topper’. Like the film The Shawshank Redemption, I suspect this marvellous item has been slow to catch on because it has been given a silly name: you feel a bit daft recommending it to your friends. If you do summon up the courage to ask ‘Have you got a mattress topper?’ most people will look bemused — but 5 to 10 per cent become highly animated ‘Best thing I’ve ever bought changes your life, etc…’

Just to explain, these devices are a kind of under-duvet. They strap on top of your mattress and create a lenient, downy layer of squidginess between the mattress and the lower sheet. They are available in down, memory-foam and lambswool variants in prices varying from about £35 to £200 and up. (Comparison is difficult, so I am not honestly sure if there is much point in buying the more expensive kinds.) As well as being luxurious, they seem significantly to improve the quality of sleep.

Now at this point you are wondering ‘Why am I reading this? This guy who works for an advertising agency has clearly been paid by a mattress-topper manufacturer to act as some kind of corporate shill. Hell, if I want the company of people who pretend to be excited about things for the purposes of their own material self–interest, I can simply visit a prostitute or read some travel journalism.’

I can assure you this is not the case here. There is no prospect of anyone paying me to advertise mattress toppers, however life-changing they may be. You see, one of the problems of hyper-efficient market capitalism is that copying products is now so fast and easy that every new market category rapidly fragments into hundreds of competing manufacturers. There is no interest in any one of them promoting the category, since their own share of any resulting growth in sales of the item would be so small. Online retail makes this worse still; whereas Argos or Peter Jones might only stock six mattress toppers, an online store can offer several hundred.

Thirty years ago, one of the incentives for creating and promoting a new idea was that, even if the idea was unpatentable, you enjoyed an effective monopoly for a few years while competitors caught up — a reward for innovation known as ‘Schumpeterian rent’. Your name might even become indelibly linked with your innovation, like Hoover or Dyson. In Australia duvets are still called Doonas after the brand name (from the Norwegian dyne?) of the first company to introduce down bedding down under.

Perfect competition isn’t always good. The faster and easier it is to copy new products, the less rewarding it is to develop them in the first place.