I never got beyond page 20 in Fifty Shades of Grey. No one got shot in the first chapter, and there were more than four characters, so I rapidly found the plot confusing. In any case, I am averse to physical pain in any form (if I were to engage in BDSM activities, my secret codeword would be ‘ouch’) so it wasn’t really my thing. But the book does leave us with one literary Everest still to be conquered: if someone can write a pornographic novel for women, is there a similar fortune to be made writing a sex-and-shopping book for men?

So that’s my plan for retirement. To write a novel for blokes where graphic scenes of deviant sexual activity are interspersed with practical, time-saving trips to Argos and B&Q. The handy thing about this is that, rather than having to construct painstaking descriptions of square-jawed characters negotiating to buy large diamonds in the cobbled streets of Antwerp, you can simply cut and paste most of it:

After he woke up, he showered and went online to reserve a Stanley FatMax FME811K Angle Grinder. £49.95. A powerful and durable angle grinder that is perfect for cutting paving slabs or other jobs requiring rapid stock removal, the Stanley FatMax Angle Grinder sports a rubber cable to prevent snapping in cold conditions and is built to an industrial standard for increased strength and durability. 850w. Disk size 115mm (disk not supplied).

Like sexual behaviour, shopping behaviour is unbelievably strange. It runs the gamut from the perfunctory to the highly theatrical. And while retailers now have a huge amount of data about who buys what, they have little clue about the underlying motivations behind it. Even economists have nothing to say about the origins of human preference. (Economics simply assumes people know perfectly what they want, and then takes it as a given that their expenditure must somehow optimally satisfy those desires.)

The only people to have asked deeper questions are evolutionary psychologists (chiefly Geoffrey Miller, Gad Saad and Robert H. Frank), who all suggest that certain patterns of consumption don’t work to our advantage. Rivalrous expenditure can degenerate into a zero-sum game: an unwinnable arms race for positional status. Expensive weddings would be a good example: can anyone honestly say they have noticed any positive correlation between how much a wedding costs and how enjoyable it is to attend? I might also suggest that the $1.7 trillion (yes, trillion) spent annually on fashion and beauty products seems a tad excessive. Frankly, if the women’s movement wants to do something really useful, women could all agree to dress down for a few years (in burkas, perhaps) and we could use the money to pay off the debt and end world hunger.

Understanding these psychological forces is important. As Tesco found, you can pursue what seems like a sensible approach for decades only to find your customers have changed. Or, if you are Amazon, you need to know how large your business could be ten years hence. Today, if you exclude things that are difficult to send by post, like petrol, plants, timber and DIY supplies, Amazon has a little over 1.1 per cent of US retail sales (yes, it seemed surprisingly small to me, too). That might mean it is perfectly possible for Amazon to become ten or even 20 times larger than it is now. Or it could be that Amazon will never be more than twice the size it is now — because, deep down in our monkey brains, we don’t really go to the shops simply to buy things we need. As I mentioned earlier, nobody has yet written a successful novel about sex and online shopping.