A roomy, elegant-yet-sporty bag with handles designed to be carried in the hand or on the wrist, with four studs on the base, the Birkin represented a new, modern statement from a fashion house known for its traditional, classical stance. Up until that point, the Kelly bag – ladylike, stiff and boxy by comparison – epitomised Hermès’ world. The only other Hermès bag to carry a celebrity moniker, their Sac à Dépêches, was renamed in 1956 after Grace Kelly was snapped using it to shield her pregnant belly, having first been introduced to the item on the set of Hitchcock’s To Catch a Thief.

The Birkin arguably played a major role in making Hermès the fashionable house it is today. “It opened Hermès up to new markets and customers, but it also changed the typical Hermès client,” says Jérôme Lalande, an antique dealer specialising in 20th-Century leather goods. “Hundreds and hundreds” of Kellys and Birkins have passed through his hands during his career, as both a long-time collaborator of Hermès, sourcing items for the house’s museums, and the bag-and-luggage expert at second-hand luxury goods specialists Collector Square, an e-boutique with a showroom on Rue Bonaparte in Paris.

In the bag

According to Lalande, the Birkin wasn’t an immediate hit: it only really took off in the late ’90s, at the dawn of the It-bag era. Thirty years on from its launch, demand is such that there is no longer a waiting list for the bag, in the classic sense of the term. “It’s a wish list, not an order list. They don’t take orders any more; you just have to hope,” says Lalande, who estimates that there are some 200,000 Birkins in circulation. And the Birkin’s limited availability has undoubtedly helped its success at auction. The most expensive bag ever to go under the hammer, according to WWD, was a red Porosus crocodile Birkin with 18-carat white-gold and diamond ‘hardware’, sold for $203,150 (£129,355) at auction in Dallas in 2011.

In the past seven years 348 have been auctioned versus 1,074 Kelly bags, according to a report by Collector Square. The rarest styles are generally the most expensive, it says, with bright colours the least common on the second-hand market. Topping the rank are pink or purple Birkins, which on average sell in leather for between 12,000 and 16,000 euros (£9,000 - £12,500).