I have arrived in my brooch era about two decades ahead of schedule. I had brooches earmarked for a later life stage, accessories that would chime with The Archers, gardening, possibly solving the odd crime in the village, that sort of thing.

But in an unexpected turn of events, I am already the correct age to wear a brooch. Not because I’m old, but because brooches have changed. They have cast off their church fete vibe and become cool. Zendaya wore a diamond serpent brooch pinned to the back of her white jacket to last year’s Met Gala. At a press conference before the recent Mexico City premiere of The Devil Wears Prada 2, Meryl Streep added no fewer than six brooches to the lapel of her pillarbox red Dolce & Gabbana suit. Pedro Pascal wore a silk Chanel camellia the size of a sunflower to the Oscars. The brooch has escaped from Granny’s jewellery box, climbed out the window and gone clubbing.

A brooch is the best thing you can do for your outfit right now. It feels fresh and new. Worn right – we are getting to that bit – it is also quite witty, which is always an enjoyable way to dress. It is timeless and elegant, and adds a dash of subversion and intrigue. And it is also fun to shop for: no need to queue for the changing room, no sizing and the real treasures are often to be found as cheap as chips at a car boot sale.

There is just one simple rule for the modern brooch-wearer. To make it crystal clear that you are in the Zendaya-at-the-Met lane rather than manning the tea urn, there should be something unexpected about your brooch. This can be size or placement or multiplication. A brooch centred on a jacket lapel is a badge of correctness. A constellation of brooches scattered across the lapel, or one the size of a dinner plate, or a brooch pinned to a scarf – that’s a different story, and a much more compelling one.

Start at the lapel. I have two vintage brooches, one gold Schiaparelli disc and one black, lacquered Chanel camellia, and most mornings at the moment I transfer them to whichever jacket I’m wearing that day. The ceremonial moment of standing in front of the mirror getting the placement right is oddly pleasing. I feel a bit proud, like I have won a rosette at the Pony Club. Which sounds eccentric, but that’s part of the brooch vibe so I’m going with it.

The weight of a brooch will change the shape of your clothes, depending where you pin it. Use this to your advantage: you want the brooch to make you look interesting, not wonky. So instead of pinning it to one side of a sweater, drape the sweater round your shoulders and fasten the brooch on the knot. Or use it to create shape and interest in a baggy T-shirt or dress by gathering and pinning some of the fabric at the side of the waist. You can even use brooches as ingenious underwear problem-solvers. I have two silver daisies that are handy for pinning at the shoulders to keep bra straps from going rogue under dress straps.

My first love, jewellery-wise, will always be earrings. Earrings are emotional and sociable and a bit flirty. Brooches are more interior, more thoughtful. Think Lady Hale and Madeleine Albright, and the royal tradition of diplomatic brooch-wearing by Queen Elizabeth II and the current Princess of Wales. The brooch may be a fashion statement right now, but it works best when it is a personal statement as well. The six brooches Streep wore for that premiere included pieces crafted from ribbons from treasured awards, including a National Medal of Arts presented to her by Barack Obama and an Order of Arts and Letters from the French state.

A brooch does not scream brand or photograph well. There is something cheerfully chaotic, pleasingly off-centre, about a sharp object you attach to yourself for no good reason, except as a small act of devotion to your mood, to the outfit you have chosen. It is personality over ego, style over fashion. Wear it as a badge of honour.

Model: Fu at Milk. Hair and makeup: Delilah Blakeney using Hair by Sam McKnight and Charlotte Tilbury. Styling assistant: Charlotte Gornall. Earrings, £175, Dower & Hall. Brooch, British Heart Foundation. Pin, £12 for 12, Asos. Cardigan, £125, Sézane. Blazer, £139.99, Mango. T-shirt, £14.90, Uniqlo