Lose five dress sizes in two minutes on my amazing Leave H&M And Go to M&S Instead Diet! That's right, I have discovered the secret to miracle slimming, and it is easy: you too can morph from a size 18 to a size 8, simply by shopping in a different place. Which is great if you want to be fooled into thinking that you're thinner, but not so handy if you just want to buy some clothes that fit.
I discovered this last week after I finally wore through the bum of my favourite jeans and had to face the shops. In H&M, I took a 10 and a 12 into the changing room. Big mistake. Huge. I had to get re-dressed and nip back into the shop twice before I learnt that, in H&M world, I am a size 18.
In case you're wondering, I'm 5ft 8in and exactly in the middle of my healthy Body Mass Index, so if I'm a size 18 then the fact that the same shop is selling adults' clothes in a UK size 4 is a little bit scary. Especially as they put the skinny sizes at the front of the racks and hide the bigger ones (18 was the largest) at the back so that big fat heifers like me have to wrestle for our enormous trousers.
Vintage dress patterns demonstrate that what we think of as standard sizes were significantly smaller in the 1950s and '60s; clothes have grown more generous to satisfy "customer optimism" around sizing. This is the case in Marks & Spencer, where I usually comfortably fit into a size 8. But we are not all like Bubbles Rothermere, who was said to have size 10 labels sewn into all her clothes (though surely anyone who saw her clothes-off could judge for himself). We just want to buy some trousers without having to try on every single pair in the shop.
So I went into Gap, where the clothes, as in men's shops, are measured in inches. The waist size on the trousers that fitted me was a good two inches smaller than I know my waist size to be, which proves that they are MIRACLE trousers! Or that an inch is not an inch on the British high street.
I have since learnt that inches vary in size for men, too (hem hem), and that blokes can also gain four inches around the waist between one shop and the next. At least clothes sizing is not purely a feminist issue.
What it is, though, is insulting. It's an insult that clothes for minuscule people are easier to buy on the high street than clothes for a healthy BMI; and it's an insult that shops waste so much of our time because they can't be bothered to learn what an inch is.
Among others, two measurable problems exist in Britain today: 1) high street shops are struggling to attract customers; and 2) young people suffer from body anxieties and often think they're fatter, or thinner, than they are. It wouldn't take a miracle to address both of them. For your next trick, Mary Portas, please give tape measures to shops.