Throughout the 1970s, the luminous British actress Jane Birkin and her partner, the French singer-songwriter Serge Gainsbourg, were the coolest couple in Paris. Jane’s signature accessory was a rustic straw basket. But in 1981 her then partner, the film director Jacques Doillon, deliberately reversed his car over it, so she boarded a flight to London carrying her belongings in a different receptacle. By chance (the story goes) she found herself sitting next Jean-Louis Dumas, head of the luxury firm Hermès, who offered to make her a better bag. A design was sketched on a handy sick-bag and the Birkin bag , that official signifier of celebrity status, as carried by Victoria Beckham, J-Lo, Lady Gaga and the ubiquitous Kardashian-Jenners, was launched. The mythology that has since accumulated around the Birkin bag is extraordinary. You can’t just wander into an Hermès shop with a wad of cash and buy one, so the market for second-hand Birkins is lively, and owners are urged to keep them in pristine condition as investments. Jane Birkin did not keep her namesake bag in pristine condition: photographs show her with it crammed so full that it can’t be closed, emblazoned with stickers supporting Unicef and Médecins du Monde, and hung about with trinkets. In 1994 she gave the original bag to be auctioned for an Aids charity. It later appeared in the V&A’s 2020 Bags: Inside Out exhibition. At some stage the trinkets and stickers were removed – though the scars of use remain: scuffs, scratches and traces of sticker adhesive. Last week this battered object was sold by Sotheby’s in Paris to a Japanese collector for €8.6 million, or £7.4 million, making it the most valuable handbag ever sold at auction. By way of context, a Titian portrait of a nobleman was sold at Christie’s earlier this month for £3.4 million. What is it that makes Jane Birkin’s knackered old handbag worth a couple of Titians? Humans are acquisitive creatures, and the things we collect tend to fall into two categories. Either their value resides in their beauty and superlative craftsmanship – such as the objects acquired by individual collectors that became the basis of museum collections such as the Ashmolean or the Wallace Collection. Alternatively, we desire objects that are perceived to have some precious numinous quality: thus the splinters of wood – enough to constitute an entire forest – supposed to be fragments of the True Cross and venerated as holy relics. In our secular age, stuff once owned by celebrities tends to fall into the latter category. In the league table of pricey celeb memorabilia, Jane Birkin’s bag comes in well below Judy Garland’s ruby slippers (£23.7 million) and level with Michael Jordan’s 1998 NBA Finals jersey. But those objects have a place in cultural history that explains their price. Birkin’s bag occupies more mysterious territory, not least because its restoration has stripped it of the idiosyncratic detail that made it distinctively hers. As a final indignity, a fashion editor has decreed that Birkin bags are “no longer cool”. Jane Birkin died in 2023, as much an icon of her times as her contemporary, Marianne Faithfull. Whether her handbag can preserve that iconic quality for posterity remains to be seen. Someone in Japan evidently thinks so. But as a lasting investment, a Titian or two might prove the better bet.