A plain black crew neck tee. High waisted light wash jeans, ripped across both knees, cuffed once at the ankle. A small black crossbody on a thin strap. A watch and a few bracelets on one wrist. That is the entire outfit, and in a square holding a couple of hundred people at dusk she is the most pulled together person in the frame. Nobody around her is wearing anything more expensive than she is. Several of them are wearing considerably more.

The formula works because it solves proportion before it solves anything else. The tee is fitted and stops just below the waistband, so the eye reads the waist high and the leg long. The jean is high rise and straight, not skinny, and the single cuff at the ankle stops the leg from swallowing the shoe. Two tones, dark on top and light below, and no third colour competing. Every decision here is about where the line sits, and none of it depends on the price of the pieces.

The black tee

This is the item most people get wrong, because a black tee is easy to buy and hard to buy well. What you want: a crew neck that sits close to the base of the neck without strangling it, a shoulder seam that lands on the corner of your shoulder bone rather than halfway down the arm, a sleeve that ends at mid bicep, and a body cut close enough to follow you without gripping. Length should hit at or just under the waistband so it works tucked or loose.

Fabric matters more than fit here. Cheap black tees go grey after four washes and turn translucent under afternoon light. Look for combed or long staple cotton, and for a knit that feels dense when you bunch it in your fist.

• Accessible: Uniqlo Supima crew, Muji, COS basics on sale
• Mid: Arket, Sunspel, ATM, Everlane
• Investment: Toteme, The Row, James Perse
• Secondhand: vintage American cotton tees on eBay and Depop, sold by weight and decade

The buying test: hold it up to a window. If you can see the outline of the window frame clearly through the fabric, it will show everything under strong light. Put it on and raise both arms. If the hem climbs above your navel, the body is too short to tuck.

The jeans

High rise, straight or slim straight, light blue with real fade rather than printed fade. The rips here sit exactly on the kneecap, which is the only place distressing looks like wear instead of decoration. Rips scattered up the thigh read as a purchase. Rips at the knee read as a jean you have owned for three years.

Rigid or lightly stretched denim holds the shape of the leg. Anything above about two percent elastane will sag at the knee by lunchtime and the rips will gape into holes.

• Accessible: Levi’s 501 and Ribcage, Weekday Rowe, Uniqlo wide fit
• Mid: Agolde, Citizens of Humanity, Frame
• Investment: Khaite, Toteme, Re/Done reworked vintage
• Secondhand: vintage Levi’s 501 in the mens sizing, which is where the good fades live

The fit test: stand normally and check where the rip falls. It should cover the kneecap when you are standing, because when you sit it will move up and open. Then do the cuff. One turn, roughly four centimetres, ending just above the ankle bone. If you need two turns the leg is too long and the hem should be cut.

The bag

Small, structured, black, on a thin strap worn across the body. The strap does the work: it draws a diagonal line across the tee and breaks up the block of black, which is why the top half of this outfit does not read flat.

What to look for: a bag that sits at the top of the hip rather than at mid thigh, a strap thin enough to look like a line rather than a belt, and a body that holds its shape when empty. Soft unstructured bags collapse into a lump against the ribs and kill the line entirely.

• Accessible: Mango, Charles & Keith, Zara leather line
• Mid: Polène, Cuyana, Wandler
• Investment: Loewe, Saint Laurent, Celine
• Secondhand: Vestiaire Collective and Fashionphile, where the small black shoulder bag is the most oversupplied category and therefore the best value

The test: wear it and put your hand flat between the bag and your hip. If there is a gap, the strap is too long. Most bags need the strap shortened by one or two holes and almost nobody does it.

The wrist

A watch with a substantial case, a couple of thin bracelets stacked beside it, all on the same wrist. Nothing on the other. That asymmetry is the whole trick, and it is the reason a two item outfit does not look unfinished.

Keep the metals consistent, or commit fully to mixing and put at least three pieces in. Two metals in two pieces looks accidental.

• Accessible: Casio vintage reissues, Timex Weekender, thin chain bracelets from Mejuri’s entry line
• Mid: Seiko 5, Timex Marlin, Monica Vinader
• Investment: Cartier Tank, Omega De Ville, a slim gold bangle you will wear daily
• Secondhand: vintage Seiko and Tissot, the best value in watches by a distance

The test: with the watch on, can you still get a shirt cuff over it? If not, it is a statement piece and it will fight every long sleeve you own.

Shoes

Low, dark, unfussy. Flat mules, ballet flats, loafers, or a plain black sneaker. The point is that the shoe finishes the leg line without introducing a new idea. A heel would tip this outfit into evening and a chunky trainer would pull it into sportswear. Both are valid, and both are a different outfit.

• Accessible: Vagabond, Mango, Adidas Sambas or Gazelles for the sneaker version
• Mid: Alohas, Dear Frances, Le Monde Béryl mules
• Investment: The Row, Manolo Blahnik flats
• Secondhand: barely worn designer flats are everywhere on resale because people buy them a half size wrong

What to change to make it yours

Swap the light denim for black if you want the outfit to run into the evening. The formula holds, it just gets sharper and less summery.

Swap the tee for a fitted rib tank in warm weather or a fine gauge black knit in cold. Same neckline, same length, same close cut.

Swap the crossbody for a shoulder bag with a short strap if the diagonal line does not suit you, and add a belt to replace the interruption it was providing.

If the rips are not for you, buy a clean light wash jean and let it wear at the knee on its own. That takes about two years and looks better than anything sold pre-distressed.

And if you own exactly one good black tee and one jean that fits, you already own this outfit. That is the point of it.

Fit is the luxury here. Everything else is cotton.

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