Tuck your shirt in. How many times, I wonder, have we heard those words from our fathers and thought to ourselves: “God, Dad, you’re soooo sad. You don’t know anything about fashion. If ever I start dressing the way you do, I’ll know I might as well give up completely.” Well, here’s the bad news: that long-dreaded moment has arrived and your dad has finally been proved right.

A tucked-in shirt really is more cool and fashionable now than a hanging-out one.

This isn’t the only trend I mean to write about in this my final column as your official men’s style adviser, but it’s certainly the most important one. White jeans will come and go. Bright colours will swiftly give way to pastels and then mushrooms, greys and blacks. But the tuck-your-shirt-in look is part of a slower-building and longer-lasting trend in men’s fashion, namely the flight from sloppy Joe casualness to clean, buttoned-up preppiness.

It started, of course, with the great suit revival pioneered three or four years ago by Hedi Slimane at Dior Homme, which suddenly got men into the idea of tailoring again. (Well, ultra-skinny men, anyway. The problem with this neat, preppy revival is that it’s biased heavily towards the young and those of a slim build. Those of ampler proportions will either have to follow Slimane’s dietary example and start living on baby-food and air or simply opt out of fashion altogether.) And once you’ve got chaps wearing fitted jackets, not just as a horrid compulsory work thing but as something pleasurable and chic, it completely changes the way they think about the rest of their wardrobe.

Last year’s great polo shirt revival — certain to continue throughout this summer — was a good example of this. Where once Ralph Lauren Polo was something you associated with ageing American investment bankers and tacky international playboy types, suddenly it was flying off the shelves of all the groovy London boutiques. Though the polo shirt had changed a teeny bit — it was now available in a slim-fit version more attractive to skinny young men — what had changed even more was the fashion cognoscenti’s state of mind. A garment that had formerly signified staid, unimaginative, square, now meant sharp, classic, hip.

Quite often I’ve advised you that you should be above such tawdry nonsense. “True style has nothing to do with fashion,” I kept saying. “It’s what you feel comfortable in that counts, not what the men’s glossies are telling you that you should wear.” But while this is all very good in theory, the truth is that fashion trends work on us so insidiously — through what we read; what we see in adverts; what we see other people wearing — that none of us, however high-minded, can remain fully immune.

I noticed this a few months ago when I started wearing collared shirts underneath V-neck sweaters. It’s a look I now like very much, especially with thick-framed glasses. It’s nerdy; it’s geeky; it says: “I’m so anti-fashion that I’m fashion.”

Yet I remember experimenting with exactly the same look a couple of years ago, and tearing off the V-neck in disgust. Back then, it was just about acceptable to wear a V-neck with a high-neck T-shirt or, better still, on bare skin, but to have done so with a collared shirt just seemed way too middle-aged-golf-dad for comfort.

So even though you may feel like saying “Pish tush” to all these spring/summer trends I’m going to tell you about, be warned: they’re going to get to you in the end. The only question is when? When they’re on the bleeding edge of hipness; when they’re fashionable but ubiquitous; or when they’re still in there, just, but fast slipping towards passé?

TUCK YOUR SHIRT IN

And yes, the rule even applies to T-shirts. You want your whole wardrobe to look sharp, fitted and clean. Imagine you’re a Mod. Or a football casual. Or maybe Ian Curtis from Joy Division, only a bit more cheery because it is spring/summer we’re talking about.

ESPADRILLES

They are this year’s summer shoe. Annoying, really, since they’re not nearly as comfortable as Birkenstocks — those rope soles don’t give nor do they grip that well — but it has to be admitted that they look great. I particularly like the stripy ones by Hudson.

Explore Women

• Fashion

• Beauty

• Diet & Fitness

• Relationships

• Families

• Celebrity

• The Way We Live

• Horoscopes

Times recommends

• How to solve the big style questions
• Aids in Africa: ‘It is the staff who really inspire you’
• Video: How to do Beyonce's 'Single Ladies' dance