Diana didn't really look like someone who'd choose a baseball cap.
The blow-dry, the Catherine Walker tailoring, the diamonds — none of it lined up with a piece of headwear that, in 1994, was basically only worn by American teenagers and people watching baseball.
And yet she picked one up on a trip to Canada and then wore it for years. Across dozens of the most-photographed off-duty frames of her life.
Somewhere in there she made the baseball cap into off-duty shorthand for women who'd never have considered one before.
There's a reason those photos are still circulating. The cap was doing more work than anyone realised at the time.
The cap she actually wore
The cap that appears in the majority of the archive is a navy six-panel cap with a small embroidered crest on the front — a Royal Canadian Mounted Police cap, picked up on a Canada trip in the late 80s.
She wore that one cap repeatedly, across years and across wildly different contexts, from the late 80s into the mid-90s.
Polo grounds. School runs. Ski trips to Lech. Weekend walks in Kensington.
The cap went everywhere with her, not the other way round.
There were a few others. A plain navy cap with large white "492" block numbers shows up in holiday frames, probably Caribbean. A handful of plain caps in navy or dark colours appear occasionally.
But the RCMP crest cap is the one the archive remembers, and the one the Pinterest feed still circulates hardest today.
She bought it herself, she wore it herself, and she wore it for long enough that it became essentially part of how she dressed.
The proportions are the thing to study.
A six-panel crown with a fairly structured front, the brim slightly curved at the peak rather than flat, the cap sitting low enough that the eyes were partly shaded but high enough that the hair was still visible underneath.
Hair almost always down, rarely up.
The cap sat on her head the way it would sit on someone who genuinely wore a cap — not someone wearing one for a photoshoot. There's a difference, and the photos make it obvious.
What made it work
What Diana did with the cap, more than anything, was take a seriousness off her own image without losing the rest of it.
Look at any of the frames and the same trick is happening.
Oversized blazer, clean white t-shirt, expensive earrings in — and then a navy baseball cap on top.
Cream raglan sweatshirt, light-wash jeans, loafers, expensive watch — and the cap on top.
Red puffer jacket, polo-neck, boots, sunglasses — cap on top.
The rest of the outfit moves from formal or polished to off-duty the moment the cap goes on, without anything else changing.
This is harder to do than it looks.
Most people who try to dress down by adding a casual piece end up dressing down everywhere else too. They pair the casual piece with more casual things, and the result is just casual.
Diana kept everything else exactly where it was. The cap did all the work.
There's also something about a baseball cap on a woman who clearly hasn't had to think about practicality that makes the whole picture relax.
The cap reads as if she's about to do something — get on with her day, go somewhere, walk the dogs — without trying to communicate that.
Function as styling, basically, but with the function genuinely there.
The blazer is still the blazer. The earrings are still in. The jeans fit.
The cap is the thing that unlocks the outfit.
What she made the cap mean
The cultural shift the cap caused isn't always remembered properly.
Before Diana, the baseball cap on a woman in London was a rarity, and on a woman like Diana, almost unthinkable.
After Diana, it became a piece a woman could wear without explanation.
The cap stopped being read as a tomboy item, or as American, or as deliberately undressed. It became a piece you could put on without making a statement about it.
Pinterest still moves on this energy.
Search "baseball cap outfit" today and a noticeable proportion of what comes back is essentially a Diana reference, whether the people pinning it know it or not.
Cap, sweatshirt or blazer, jeans or the polished version of whatever else. The proportions are hers.
The reading of the cap as something an off-duty woman wears comfortably — also hers.
Thirty years on, the look hasn't aged a day.
The reason isn't that it was ahead of its time. The reason is that it was so completely well-judged in its own moment that it became permanent.
How to wear it now
The cap as a wardrobe piece, in 2026, is essentially the same thing it was in 1993.
Plain colour, navy or dark. A crest if it earns its place, but never a fashion logo — Diana's RCMP crest worked because it was a genuine object with a reason to exist, not a styling choice.
The brim curved slightly, not flat.
Worn with the rest of the outfit doing its proper thing — the blazer, the loafers, the watch you don't take off.
The way Diana wore it suggests three places where the cap earns its keep.
First, with a blazer over a t-shirt and jeans, as an off-duty weekend look that still has some tailoring in it.
Second, with a sweatshirt and jeans, on the way to or from something ordinary — a walk, a school run, the papers.
Third, with a winter coat and something warm underneath, the way she wore it in Lech over the red puffer.
None of these requires anything new. The cap just shifts the register of what's already in the wardrobe.
A British legacy
It's been close to thirty years since Diana last wore that RCMP cap in public, and the photos haven't lost anything.
They might be the most reliably referenced wardrobe images of the last hundred years of British style.
There's a reason for that — the cap picked up on a trip, worn for years, doing the same small job every time.
None of it trying. All of it landing.