Fashion has one rule that marketing hates to admit: the most expensive piece is not the newest one, but the one you can no longer buy. Hailey Bieber knows this better than most. At a dinner in London this week, in front of partners, friends and business colleagues, she showed up in a dress from Narciso Rodriguez's spring/summer 1997 collection.

The occasion was the London arrival of OBB Media, the entertainment company of Michael D. Ratner - husband of Lauren Ratner, who co-founded the Rhode brand with Hailey. The styling was by Dani Michelle, one of her trusted stylists. The dress is long and body-skimming, with a V-neckline and wide straps, in a champagne shade and inspired by the classic slip dress. It is cut on the bias, along the diagonal of the fabric, and covered in a fine mesh of crystals - the detail nobody saw coming.

The styling followed a formula familiar from thirty years ago. No statement jewellery, all the attention on the lines of the cut and the neckline. The only accessory was a pair of strappy gold heeled sandals. That is exactly Carolyn Bessette-Kennedy's recipe: little, but perfectly chosen.

The connection is no accident. Carolyn and Narciso met while working at Calvin Klein. When she began planning her wedding to John F. Kennedy's son, she trusted him with her wedding dress - out of friendship and out of a wish to give him visibility. He created the unforgettable silk slip dress she wore on her big day. The design then went into the spring/summer 1997 collection under the name Ceruti. Almost thirty years later, Hailey has put it back in play.

The timing is calculated to the millimetre. A few months ago the series Love Story put Carolyn and John F. Kennedy Jr. back in the spotlight, and with them their wardrobe: basics, simple cuts, accessories in just the right measure. A style that three decades on is still a source of inspiration - and, evidently, of good publicity.

From London, straight to Paris. On 29 September Hailey sat in the front row at the Saint Laurent show, this time in a completely different story: a black suit with a slightly roomy jacket and straight trousers, pointed pumps and black sunglasses. From silk and crystals to a strict black suit - versatility is her strongest card.

The question for those of us looking at these photos is as old as fashion itself: does "less is more" really hold when that "less" is an archival piece from 1997 that nobody else can wear?