Dia-damn! The Countess of Rosebery dons the historic diamond-winged Cartier Valkyrie Tiara at the British Museum Ball 2026

Society swans and silver screen starlets alike were seeing red at the British Museum’s annual gala this weekend. Following on from last year’s cerise-hued dress code, attendees at the Great Russell Street institution’s glittering event searched for shimmering scarlet silks to cascade around themselves as they headed through the threshold to find their pews at this year’s coveted affair. Lady Kitty Lewis opted for Dolce & Gabbana Alta Moda; the Marchioness of Bath called upon Lebanese courtier, Nicolas Jebran. Meanwhile, the Countess of Rosebery chose a custom, goddess-like ensemble from Gallello Atelier for her elegant appearance.

It was, undeniably, a rather gorgeous silhouette. However, equally as beguiling was the diamond-encrusted diadem which sat atop her neatly tucked brunette updo. The ultimate gallery glamazon – and wife of Sotheby’s chairman, the Earl of Rosebery – accessorised with a simply stunning and thoroughly historic headpiece: the Cartier Valkyrie Tiara. 'Harry and I are committee members for the ball and wanted to do something very special this year. I have actually never seen an image of the tiara being worn and thought that this would be the right moment to commemorate it, given that the British Museum is home to some of the world's greatest objects,' the Countess tells Tatler. ‘This was an evening to celebrate that and all that they do to bring us in touch with our collective past. For example, bringing the Bayeux Tapestry back to England for the first time since its creation. So it just felt like this was the appropriate setting for it.'

Last seen on display publicly at the V&A Dundee as part of the Scottish museum’s maiden exhibitions which opened in 2018, the piece features 2,500 brilliant-cut, single-cut, rose-cut and baguette diamonds set in a gold and silver frame, with two wing-like festoons sprouting out from above the ears. It comes with its own memoir of seismic society glamour, too, having been first commissioned by the Duchess of Roxburghe - the Earl's great aunt - in 1935, when she decided to have it made to honour her husband’s Scottish family dynasty the year she wed at Westminster Abbey. She later left it to Harry, then Lord Dalmeny.

Crafted by Cartier - and the last of its style to be created by the French heritage jewellers - its ethereal outline pays homage to Norse mythology, particularly of its namesake folklore figure, the Valkyrie, and the character of the same name in Richard Wagner’s opera, Der Ring des Nibelungen. Serving the god, Odin, the ‘chooser of the slain’ is described as being responsible for selecting who dies in battle and who goes to the afterlife, according to ancient texts.

Rosebery’s choice to embrace the tiara's poignant pointed ears was nonetheless a seriously stylish move. ‘Gallello Atelier made me the most beautiful gown that I feel just worked perfectly with the language of the Valkyrie Tiara. I wanted to look like a sculpture that had just stepped down from its plinth... The image of Audrey Hepburn descending the stairs in the Louvre in front of the Winged Victory of Samothrace (Funny Face, 1957) just kept recurring whenever I thought about this look, and I wanted to capture something of that cinematic moment,’ Rosebery reveals.

She now joins a roster of fashionable figures who have had their Valkyrie-inspired crowning moments. Jane Norton Grew, wife of American banker, J.P. Morgan Jr, had Cartier craft her a tiara comprising wings surrounding a 33-carat central diamond. Around the turn of the 20th century, US First Lady Ida Saxton McKinley, wife of William McKinley, had her own diadem created. (Although, in an unusual twist, this treasure ended up on the reality television programme, Pawn Stars, in 2014, before being returned to the family's collection).

It’s not all Greek to tinseltown's leading fashion figures either. In fact, wings themselves have been a recurring theme on glitzy international red carpets as of late. At the New York premiere of The Odyssey, Athena embodier, Zendaya, slipped into huge white plumes which erupted from the back of her Matières Fécales gown. And Kendall Jenner turned to Zac Posen to honour the goddess, Nike, for her tribute to the aforementioned Hellenistic sculpture, Winged Victory of Samothrace at the Met Gala back in May.

High flyers and even higher glamour: consider ascending to the skies for inspiration for gala season's most airborne - and elegant - trend. As the Countess puts it herself, she felt ‘hugely honoured’ and ‘deeply grateful’ to wear the piece. Those looking to try out a similarly art-informed style for themselves might just want to follow la rue de Rosebery for motivation…